Corpus

The authors report on an interesting study I have some specific comments below. To summarize, some essential elements are missing from the manuscript, and the manuscript needs significant editorial attention (errors, academic writing style, figures).

Abstract High frequency hearing loss is one of the most common problems in the aging population and with those who have a history of exposure to loud noises. To address high-frequency hearing loss, we developed a multi-motor wristband that uses machine learning to listen for specific high frequency phonemes. The wristband vibrates in spatially unique locations to represent which phoneme was present, in real time. We recruited 16 participants with high frequency hearing loss and asked them to wear the wristband for six weeks. Their degree of disability associated with hearing loss was measured weekly using the Abbreviated Profile of Hearing Aid Benefit (APHAB). Our findings show that vibrotactile sensory substitution delivered by a wristband that produces spatially distinguishable vibrations in correspondence with high frequency phonemes helps individuals with high frequency hearing loss improve their understanding of verbal communication. We find that vibrotactile feedback provides benefits whether or not a person wears hearing aids, albeit in slightly different ways. Finally, our results also demonstrate that individuals with the greatest difficulty understanding speech prior to the study experience the greatest amount of benefit from vibrotactile feedback.

BACKGROUND: High-frequency hearing loss is one of the most common problems in the aging population and with those who have a history of exposure to loud noises. This type of hearing loss can be frustrating and disabling, making it difficult to understand speech communication and interact effectively with the world. OBJECTIVE: This study aimed to examine the impact of spatially unique haptic vibrations representing high-frequency phonemes on the self-perceived ability to understand conversations in everyday situations. METHODS: To address high-frequency hearing loss, a multi-motor wristband was developed that uses machine learning to listen for specific high-frequency phonemes. The wristband vibrates in spatially unique locations to represent which phoneme was present in real time. A total of 16 participants with high-frequency hearing loss were recruited and asked to wear the wristband for 6 weeks. The degree of disability associated with hearing loss was measured weekly using the Abbreviated Profile of Hearing Aid Benefit (APHAB). RESULTS: =2.14; P=.10, 2-tailed independent t test). The average benefit score across all participants for ease of communication was 15.44 (SD 13.88; N=16; P<.001, 2-tailed dependent t test). The average benefit score across all participants for background noise was 10.88 (SD 17.54; N=16; P=.03, 2-tailed dependent t test). The average benefit score across all participants for reverberation was 10.84 (SD 16.95; N=16; P=.02, 2-tailed dependent t test). CONCLUSIONS: These findings show that vibrotactile sensory substitution delivered by a wristband that produces spatially distinguishable vibrations in correspondence with high-frequency phonemes helps individuals with high-frequency hearing loss improve their perceived understanding of verbal communication. Vibrotactile feedback provides benefits whether or not a person wears hearing aids, albeit in slightly different ways. Finally, individuals with the greatest perceived difficulty understanding speech experienced the greatest amount of perceived benefit from vibrotactile feedback.

The need for a meaningful test for intelligence in AI becomes increasingly pressing as AI systems grow more sophisticated. Several approaches have been proposed for intelligence tests, ranging from solving puzzles, understanding natural language, or learning and adapting to new situations. I here propose that instead of assessing intelligence based on conversational text (Turing test) or creativity (Lovelace test), a superior test assesses the capacity to make scientific discovery. However, it is critical to note there are different categories of such discovery. Level 1 discovery is defined here as piecing together scattered facts in the scientific literature, something that approaches impossibility for a human who cannot read the literature in its entirety nor enjoy perfect recall. Level 1 discoveries will be meaningful and important, but there is an important distinction to be drawn: Level 2 discoveries require the building and simulation of new models rather than simply a joining of facts. Einstein’s discovery of special relativity or Darwin’s proposal of evolution by natural selection are examples that extend beyond simple interpolation and instead require novel frameworks. In summary, scientific discovery can serve as a meaningful test of intelligence – but this requires distinguishing different levels, and in this proposal only Level 2 discoveries will serve to demonstrate human-level intelligence.

Haptic devices use the sense of touch to transmit information to the nervous system. As an example, a sound-to-touch device processes auditory information and sends it to the brain via patterns of vibration on the skin for people who have lost hearing. We here summarize the current directions of such research and draw upon examples in industry and academia. Such devices can be used for sensory substitution (replacing a lost sense, such as hearing or vision), sensory expansion (widening an existing sensory experience, such as detecting electromagnetic radiation outside the visible light spectrum), and sensory addition (providing a novel sense, such as magnetoreception). We review the relevant literature, the current status, and possible directions for the future of sensory manipulation using non-invasive haptic devices.

Tinnitus (ringing in the ears) affects 1 in 10 adults in the United States, often with damaging psychological consequences. Currently, there exists no cure for most forms of tinnitus. Recently, bimodal stimulation - the pairing of sounds with haptic stimulation - has shown efficacy in reducing the symptoms of tinnitus. Previous bimodal stimulation approaches have used electrical shocks on the tongue, a technique that requires daily in-person sessions at an audiologist's office. We here show that excellent results can be achieved wearing a wristband with multiple vibratory motors. Tones are played and the wristband correspondingly vibrates the wrist of the user at different spatial locations depending on the frequency of the tone. We compared the experimental group with a control group who listened to the tones but did not wear the wristband. The tone frequencies were centered on each user's tinnitus frequency and the tones were randomized both in frequency and duration. 45 participants with Tinnitus Functional Index (TFI) scores of 25 and above were tested. Results show a significantly greater reduction in TFI scores for the experimental group compared to the control. Importantly, with higher baseline severity we find larger differences between the experimental and control groups, revealing greater symptom improvement for those with severe tinnitus. The therapeutic approach of combining sounds with spatiallyand temporally-correlated vibrations on the wrist is found to be a simple, time-efficient, and effective procedure to lessen the symptoms of tinnitus.

Merker, Williford, and Rudrauf make several arguments against the integrated information theory of consciousness; whereas some have merit, their conclusion that the theory should be discarded is premature. Coming years promise advances in the empirical study of consciousness, and only after theories are independently tested with shared data can they be ruled in or out. We propose future research directions.

Abstract Merker, Williford, and Rudrauf make several arguments against the integrated information theory of consciousness; whereas some have merit, their conclusion that the theory should be discarded is premature. Coming years promise advances in the empirical study of consciousness, and only after theories are independently tested with shared data can they be ruled in or out. We propose future research directions.

Abstract Tinnitus (ringing in the ears) affects 1 in 10 adults in the United States, often with damaging psychological consequences. Currently, there exists no cure for most forms of tinnitus. Recently, bimodal stimulation – the pairing of sounds with haptic stimulation – has shown efficacy in reducing the symptoms of tinnitus. Previous bimodal stimulation approaches have used electrical shocks on the tongue, a technique that requires daily in-person sessions at an audiologist’s office. We here show that excellent results can be achieved wearing a wristband with multiple vibratory motors. Tones are played and the wristband correspondingly vibrates the wrist of the user at different spatial locations depending on the frequency of the tone. We compared the experimental group with a control group who listened to the tones but did not wear the wristband. The tone frequencies were centered on each user’s tinnitus frequency and the tones were randomized both in frequency and duration. 45 participants with Tinnitus Functional Index (TFI) scores of 25 and above were tested. Results show a significantly greater reduction in TFI scores for the experimental group compared to the control. Importantly, with higher baseline severity we find larger differences between the experimental and control groups, revealing greater symptom improvement for those with severe tinnitus. The therapeutic approach of combining sounds with spatially- and temporally-correlated vibrations on the wrist is found to be a simple, time-efficient, and effective procedure to lessen the symptoms of tinnitus.

Through collaborations among diplomats, scientists, and engineers, authors envision artificial intelligence (AI) paired with emerging human augmentation technologies significantly improving the bandwidth, speed, and optimality of diplomacy.

Time perception is fluid and affected by manipulations to visual inputs. Previous literature shows that changes to low-level visual properties alter time judgments at the millisecond-level. At longer intervals, in the span of seconds and minutes, high-level cognitive effects (e.g., emotions, memories) elicited by visual inputs affect time perception, but these effects are confounded with semantic information in these inputs, and are therefore challenging to measure and control. In this work, we investigate the effect of asemantic visual properties (pure visual features devoid of emotional or semantic value) on interval time perception. Our experiments were conducted with binary and production tasks in both conventional and head-mounted displays, testing the effects of four different visual features (spatial luminance contrast, temporal frequency, field of view, and visual complexity). Our results reveal a consistent pattern: larger visual changes all shorten perceived time in intervals of up to 3min, remarkably contrary to their effect on millisecond-level perception. Our findings may help alter participants' time perception, which can have broad real-world implications.

Moist is a common example of a word that triggers aversion or disgust responses in many people. Word aversion presents a novel opportunity to empirically study the link between linguistic features (phonology, semantics) and emotional response. In the present study, we (1) determine the prevalence and extent of aversions to specific words in a large cohort, (2) examine phonological predictors of emotional response in word aversion, and (3) test the effect of phonological-emotional mapping on processing in an object-labeling paradigm. Across 244 participants, individuals tended to rate a subset of commonly self-reported aversive words (e.g. slacks) as more aversive than matched control words. However, participants reported even stronger aversions to nonsense words, suggesting that familiarity may moderate the experience of word aversion. Results also suggest that word-averse individuals make associations between phonology and meaning more readily.

Regions of the brain maintain their territory with continuous activity: if activity slows or stops (e.g., because of blindness), the territory tends to be taken over by its neighbors. A surprise in recent years has been the speed of takeover, which is measurable within an hour. These findings lead us to a new hypothesis on the origin of REM sleep. We hypothesize that the circuitry underlying REM sleep serves to amplify the visual system's activity periodically throughout the night, allowing it to defend its territory against takeover from other senses. We find that measures of plasticity across 25 species of primates correlate positively with the proportion of rapid eye movement (REM) sleep. We further find that plasticity and REM sleep increase in lockstep with evolutionary recency to humans. Finally, our hypothesis is consistent with the decrease in REM sleep and parallel decrease in neuroplasticity with aging.

Traditionally, recording from and stimulating the brain with high spatial and temporal resolution required invasive means. However, recently, the technical capabilities of less invasive and non-invasive neuro-interfacing technology have been dramatically improving, and laboratories and funders aim to further improve these capabilities. These technologies can facilitate functions such as multi-person communication, mood regulation and memory recall. We consider a potential future where the less invasive technology is in high demand. Will this demand match that the current-day demand for a smartphone? Here, we draw upon existing research to project which particular neuroethics issues may arise in this potential future and what preparatory steps may be taken to address these issues.

Abstract Aim Despite its high frequency of occurrence, mild traumatic brain injury (mTBI), or concussion, is difficult to recognize and diagnose, particularly in pediatric populations. Conventional methods to diagnose mTBI primarily rely on clinical questionnaires and sometimes include imaging such as computed tomography (CT) or pencil and paper neuropsychological testing. However, these methods are time consuming, require administration/interpretation from health professionals, and lack adequate test sensitivity and specificity. We explore the use of BrainCheck, a computerized neurocognitive test that is available on iPad, iPhone or computer desktop, for mTBI assessment. The BrainCheck battery consists of 6 gamified traditional neurocognitive tests that assess areas of cognition vulnerable to mTBI such as attention, processing speed, executing functioning, and coordination. Methods We administered BrainCheck to 10 participants diagnosed with mTBI at the emergency department (ED) of Children’s hospital within 96 hours of admittance to the ED, and 126 normal controls at a local high school. Statistical analysis included Chi-Square tests, Analysis of Variance (ANOVA), independent sample t-tests, and Hochberg tests to examine differences between mTBI, diagnoses by current gold standard clinical exam, and control groups on each assessment in the battery. Significant metrics from these assessments were used to build a logistic regression model that distinguishes mTBI from non-mTBI participants. Results BrainCheck was able to detect significant differences in coordination, Flanker, Stroop, Digital Symbol, Immediate/Delayed recall and recognition assessments between normal people and mTBI patients. Receiver operator score (ROC) analysis of our logistic regression model found a sensitivity of 84% and specificity of 80%. Conclusions BrainCheck has potential in distinguishing mTBI from non-mTBI participants, by providing a shorter, gamified test battery to assess cognitive function after brain injury, while also providing a method for tracking recovery with the opportunity to do so remotely from a patient’s home.

Background: Acute ingestion of alcohol impairs cognitive function and poses significant threat to public health and safety with impaired operation of motor vehicles. However, there is a lack of access to tools to assess one's cognitive impairment due to alcohol. The purpose of this study was to explore the use of a neuropsychological assessment software, BrainCheck, to assess levels of alcohol impairment based on performance on the neuropsychological assessments. Methods: We administered the BrainCheck battery to 91 volunteer participants. Participants were required to take a baseline battery prior to any alcohol ingestion, and another testing battery after a voluntary drinking period. Blood alcohol concentration (BAC) for the participant was obtained using a breathalyzer. We performed statistical analysis comparing alcohol vs. non-alcohol performance on the BrainCheck battery, and used significant metrics of these assessments to generate predictive models. Results: Statistical analyses were performed comparing participants performance on the BrainCheck battery before and after alcohol consumption. Comparison was also done comparing performance between an intoxicated group with a BAC &gt; 0.05, and a sober group with a BAC ≤ 0.05. Two assessment metrics were found to be significant among comparison groups after P-value correction, and four test metrics were observed to moderately correlate (|r| &gt; 0.40) with BAC levels. Three linear regression models (least-squares, ridge and LASSO) were built to predict participant BAC levels, with the best performing model being the least-squares model with a RMSE of 0.027. We also built a predictive logistic regression model to detect whether the participant is intoxicated or not, with 80.6% accuracy, 73.3% sensitivity, and 75.0% specificity. Discussion: The BrainCheck battery has potential to predict alcohol impairment, including participant BAC levels and if the participant is intoxicated or not. BrainCheck provides another option to assess an individual's cognitive impairment due to alcohol, with the utility of being portable and available on one's smartphone.

Traditional pen and paper based neuropsychological tests (NPT) for cognition assessment have several challenges limiting their use. They are time consuming, expensive, and require highly trained specialists to administer. This leads to testing being available to only a small portion of the population and often with wait times of several months. In clinical practice, we have found results tend not to be integrated effectively into assessment and plans of the ordering provider. Here we compared several tests using BrainCheck (BC), a computer-based NPT battery, to traditional paper-based NPT, by evaluating individual tests as well as comparing composite scores to scores on traditional screening tools. 26 volunteers took both paper-based tests and BC. We found scores of four assessments (Ravens Matrix, Digit Symbol Modulation, Stroop Color Word Test and Trails Making A&amp;B Test) were highly correlated. The Balance Examination and Immediate/Delayed Hopkins Verbal Learning, however, were not correlated. The BC composite score was correlated to results of the Saint Louis University Mental Status (SLUMS) exam [1], the Mini-Mental State Examination (MMSE) [2], and the Montreal Cognitive Assessment (MoCA). Our results suggest BC may offer a computer-based avenue to address the gap between basic screening and formal neuropsychological testing.

Abstract Regions of the brain maintain their territory with continuous activity: if activity slows or stops (e.g., because of blindness), the territory tends to be taken over by its neighbors. A surprise in recent years has been the speed of takeover, which is measurable within an hour. These findings lead us to a new hypothesis on the origin of dream sleep. We hypothesize that the circuitry underlying dreaming serves to amplify the visual system’s activity periodically throughout the night, allowing it to defend its territory against takeover from other senses. We find that measures of plasticity across 25 species of primates correlate positively with the proportion of rapid eye movement (REM) sleep. We further find that plasticity and REM sleep increase in lockstep with evolutionary recency to humans. Finally, our hypothesis is consistent with the decrease in REM sleep and parallel decrease in neuroplasticity with aging.

Time perception is fluid, and can change in response to different visual inputs. Previous literature shows that time perception at short (millisecond timing) intervals is affected by low-level aspects of visual stimuli, including luminance contrast and temporal frequency. At long intervals, high-level aspects like emotions elicited by visual input affect time perception, but are confounded with semantics. For the first time, we investigate the effects of changes in low-level aspects of visual input on time perception at long intervals (30 seconds to 3 minutes). We conduct experiments in traditional displays (TD) and virtual reality (VR), and find that luminance contrast, temporal frequency of presentation, and field of view (FoV; tested in VR only) have significant effects on time perception. Using a 2AFC task, participants judge whether less or more than half of a trial’s duration has elapsed at a given sampling point (45% or 55% of the total trial duration). Prior to each experiment, participants are presented with a sample trial and told when 50% of the time has elapsed. Participants perform 8-12 trials at a fixed viewing duration. First, we find that contrast and frequency have significant effects on time judgements of 30s trials with static images in TD. Second, we replicate these results in VR, and also find a significant effect of FoV. Third, the effects of contrast and frequency hold up when using 30s trials of video clips in TD. Fourth, we extend our experiments to longer blocks of up to 3 minutes while varying stimuli frequency, and find consistent results. Our results show that higher frequency, higher contrast, and larger FoV (bigger visual magnitude changes) shorten perceived time. These results provide a means of modifying visual stimuli to change their perceived duration.

We seek to address current limitations of forensic risk assessments by introducing the first mobile, self-scoring, risk assessment software that relies on neurocognitive testing to predict reoffense. This assessment, run entirely on a tablet, measures decision-making via a suite of neurocognitive tests in less than 30 minutes. The software measures several cognitive and decision-making traits of the user, including impulsivity, empathy, aggression, and several other traits linked to reoffending. Our analysis measured whether this assessment successfully predicted recidivism by testing probationers in a large urban city (Houston, TX, United States) from 2017 to 2019. To determine predictive validity, we used machine learning to yield cross-validated receiver-operator characteristics. Results gave a recidivism prediction value of 0.70, making it comparable to commonly used risk assessments. This novel approach diverges from traditional self-reporting, interview-based, and criminal-records-based approaches, and can also add a protective layer against bias, while strengthening model accuracy in predicting reoffense. In addition, subjectivity is eliminated and time-consuming administrative efforts are reduced. With continued data collection, this approach opens the possibility of identifying different levels of recidivism risk, by crime type, for any age, or gender, and seeks to steer individuals appropriately toward rehabilitative programs. Suggestions for future research directions are provided.

Aim: Despite its high frequency of occurrence, mild traumatic brain injury (mTBI), or concussion, is difficult to recognize and diagnose, particularly in pediatric populations. Conventional methods to diagnose mTBI primarily rely on clinical questionnaires and sometimes include neuroimaging or pencil and paper neuropsychological testing. However, these methods are time consuming, require administration/interpretation from health professionals, and lack adequate test sensitivity and specificity. This study explores the use of BrainCheck Sport, a computerized neurocognitive test that is available on iPad, iPhone, or computer desktop, for mTBI assessment. The BrainCheck Sport Battery consists of 6 gamified traditional neurocognitive tests that assess areas of cognition vulnerable to mTBI such as attention, processing speed, executing functioning, and coordination. Methods: We administered BrainCheck Sport to 10 participants diagnosed with mTBI at the emergency department of Children’s hospital or local high school within 96 hours of injury, and 115 normal controls at a local high school. Statistical analysis included Mann-Whitney U test, chi-square tests, and Hochberg tests to examine differences between the mTBI group and control group on each assessment in the battery. Significant metrics from these assessments were used to build a logistic regression model that distinguishes mTBI from control participants. Results: BrainCheck Sport was able to detect significant differences in Coordination, Stroop, Immediate/Delayed Recognition between normal controls and mTBI patients. Receiver operating characteristic (ROC) analysis of our logistic regression model found a sensitivity of 84% and specificity of 81%, with an area under the curve of 0.884. Conclusions: BrainCheck Sport has potential in distinguishing mTBI from control participants, by providing a shorter, gamified test battery to assess cognitive function after brain injury, while also providing a method for tracking recovery with the opportunity to do so remotely from a patient’s home.

BACKGROUND: The US population over the age of 65 is expected to double by the year 2050. Concordantly, the incidence of dementia is projected to increase. The subclinical stage of dementia begins years before signs and symptoms appear. Early detection of cognitive impairment and/or cognitive decline may allow for interventions to slow its progression. Furthermore, early detection may allow for implementation of care plans that may affect the quality of life of those affected and their caregivers. OBJECTIVE: We sought to determine the accuracy and validity of BrainCheck Memory as a diagnostic aid for age-related cognitive impairment, as compared against physician diagnosis and other commonly used neurocognitive screening tests, including the Saint Louis University Mental Status (SLUMS) exam, the Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment (MoCA). METHODS: We tested 583 volunteers over the age of 49 from various community centers and living facilities in Houston, Texas. The volunteers were divided into five cohorts: a normative population and four comparison groups for the SLUMS exam, the MMSE, the MoCA, and physician diagnosis. Each comparison group completed their respective assessment and BrainCheck Memory. RESULTS: A total of 398 subjects were included in the normative population. A total of 84 participants were in the SLUMS exam cohort, 51 in the MMSE cohort, 35 in the MoCA cohort, and 18 in the physician cohort. BrainCheck Memory assessments were significantly correlated to the SLUMS exam, with coefficients ranging from .5 to .7. Correlation coefficients for the MMSE and BrainCheck and the MoCA and BrainCheck were also significant. Of the 18 subjects evaluated by a physician, 9 (50%) were healthy, 6 (33%) were moderately impaired, and 3 (17%) were severely impaired. A significant difference was found between the severely and moderately impaired subjects and the healthy subjects (P=.02). We derived a BrainCheck Memory composite score that showed stronger correlations with the standard assessments as compared to the individual BrainCheck assessments. Receiver operating characteristic (ROC) curve analysis of this composite score found a sensitivity of 81% and a specificity of 94%. CONCLUSIONS: BrainCheck Memory provides a sensitive and specific metric for age-related cognitive impairment in older adults, with the advantages of a mobile, digital, and easy-to-use test. TRIAL REGISTRATION: ClinicalTrials.gov NCT03608722; https://clinicaltrials.gov/ct2/show/NCT03608722 (Archived by WebCite at http://www.webcitation.org/76JLoYUGf).

<sec> <title>BACKGROUND</title> The US population over the age of 65 is expected to double by the year 2050. Concordantly, the incidence of dementia is projected to increase. The subclinical stage of dementia begins years before signs and symptoms appear. Early detection of cognitive impairment and/or cognitive decline may allow for interventions to slow its progression. Furthermore, early detection may allow for implementation of care plans that may affect the quality of life of those affected and their caregivers. </sec> <sec> <title>OBJECTIVE</title> We sought to determine the accuracy and validity of BrainCheck Memory as a diagnostic aid for age-related cognitive impairment, as compared against physician diagnosis and other commonly used neurocognitive screening tests, including the Saint Louis University Mental Status (SLUMS) exam, the Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment (MoCA). </sec> <sec> <title>METHODS</title> We tested 583 volunteers over the age of 49 from various community centers and living facilities in Houston, Texas. The volunteers were divided into five cohorts: a normative population and four comparison groups for the SLUMS exam, the MMSE, the MoCA, and physician diagnosis. Each comparison group completed their respective assessment and BrainCheck Memory. </sec> <sec> <title>RESULTS</title> A total of 398 subjects were included in the normative population. A total of 84 participants were in the SLUMS exam cohort, 51 in the MMSE cohort, 35 in the MoCA cohort, and 18 in the physician cohort. BrainCheck Memory assessments were significantly correlated to the SLUMS exam, with coefficients ranging from .5 to .7. Correlation coefficients for the MMSE and BrainCheck and the MoCA and BrainCheck were also significant. Of the 18 subjects evaluated by a physician, 9 (50%) were healthy, 6 (33%) were moderately impaired, and 3 (17%) were severely impaired. A significant difference was found between the severely and moderately impaired subjects and the healthy subjects (P=.02). We derived a BrainCheck Memory composite score that showed stronger correlations with the standard assessments as compared to the individual BrainCheck assessments. Receiver operating characteristic (ROC) curve analysis of this composite score found a sensitivity of 81% and a specificity of 94%. </sec> <sec> <title>CONCLUSIONS</title> BrainCheck Memory provides a sensitive and specific metric for age-related cognitive impairment in older adults, with the advantages of a mobile, digital, and easy-to-use test. </sec> <sec> <title>CLINICALTRIAL</title> ClinicalTrials.gov NCT03608722; https://clinicaltrials.gov/ct2/show/NCT03608722 (Archived by WebCite at http://www.webcitation.org/76JLoYUGf) </sec>

Watching another person in pain activates brain areas involved in the sensation of our own pain. Importantly, this neural mirroring is not constant; rather, it is modulated by our beliefs about their intentions, circumstances, and group allegiances. We investigated if the neural empathic response is modulated by minimally-differentiating information (e.g., a simple text label indicating another’s religious belief), and if neural activity changes predict ingroups and outgroups across independent paradigms. We found that the empathic response was larger when participants viewed a painful event occurring to a hand labeled with their own religion (ingroup) than to a hand labeled with a different religion (outgroup). Counterintuitively, the magnitude of this bias correlated positively with the magnitude of participants’ self-reported empathy. A multivariate classifier, using mean activity in empathy-related brain regions as features, discriminated ingroup from outgroup with 72% accuracy; the classifier’s confidence correlated with belief certainty. This classifier generalized successfully to validation experiments in which the ingroup condition was based on an arbitrary group assignment. Empathy networks thus allow for the classification of long-held, newly-modified and arbitrarily-formed ingroups and outgroups. This is the first report of a single machine learning model on neural activation that generalizes to multiple representations of ingroup and outgroup. The current findings may prove useful as an objective diagnostic tool to measure the magnitude of one’s group affiliations, and the effectiveness of interventions to reduce ingroup biases.

We describe a patient LS, profoundly deaf in both ears from birth, with underdeveloped superior temporal gyri. Without hearing aids, LS displays no ability to detect sounds below a fixed threshold of 60 dBs, which classifies him as clinically deaf. Under these no-hearing-aid conditions, when presented with a forced-choice paradigm in which he is asked to consciously respond, he is unable to make above-chance judgments about the presence or location of sounds. However, he is able to make above-chance judgments about the content of sounds presented to him under forced-choice conditions. We demonstrated that LS has faint sensations from auditory stimuli, but questionable awareness of auditory content. LS thus has a form of type-2 deaf hearing with respect to auditory content. As in the case of a subject with acquired deafness and deaf hearing reported on a previous occasion, LS’s condition of deaf hearing is akin in some respects to type-2 blindsight. As for the case of type 2 blindsight the case indicates that a form of conscious hearing can arise in the absence of a fully developed auditory cortex.

This study analyzes the law enforcement response to prostitution in Houston, Texas, between 1977 and 2010 to examine whether the traditional approach to policing prostitution disproportionately penalizes women. Data included the disposition and sentencing information for 22,916 first-time prostitution arrests in Harris County. Using bivariate and multivariate analyses, we explored gender differences in the likelihood of receiving punishment, the type(s) of punishment received, and the amount of punishment for first-time prostitution offenses. We find that women were disproportionately arrested for prostitution and that women were more likely to receive a jail sentence for involvement in prostitution than men were. In contrast, male arrestees for prostitution were more likely to receive probation sentences and/or fines. This study adds to a robust body of literature suggesting that gender impacts sentencing in the criminal justice system. Yet, it is unclear whether the role of the arrestee—as either a buyer or seller—moderates the effect of gender. This quandary demonstrates the need for more comprehensive data collection about the role of the arrestee in the commercial sexual exchange.

Risk assessment has become a prominent part of the criminal justice system in many jurisdictions, typically relying on structured questions and an interview. This approach, however, may not accurately assess certain psychological concepts correlated with reoffense, such as executive functioning, ability to plan, impulse control, risk-taking, aggression, and empathy. We hypothesized that using rapid-tablet-based neurocognitive tests would pay off in terms of objectivity, precision, and scalability when added to the existing risk assessment structure. We analyzed 240 observations from adult felony offenders from a large urban county in the South assessed by the Texas version of the Ohio Risk Assessment System (ORAS) risk tool. We identified significant differences in impulse control, planning, and reactive aggression between offenders and reoffenders. By combining these variables with the Texas Risk Assessment System (TRAS), we yielded significant improvements in risk prediction. We hope this will provide new inroads for actuarial assessments of reoffense risk that incorporate direct measurements of individual decision making.

Despite the high prevalence of traumatic brain injuries (TBI), there are few rapid and straightforward tests to improve its assessment. To this end, we developed a tablet-based software battery ("BrainCheck") for concussion detection that is well suited to sports, emergency department, and clinical settings. This article is a study of the diagnostic accuracy of BrainCheck. We administered BrainCheck to 30 TBI patients and 30 pain-matched controls at a hospital Emergency Department (ED), and 538 healthy individuals at 10 control test sites. We compared the results of the tablet-based assessment against physician diagnoses derived from brain scans, clinical examination, and the SCAT3 test, a traditional measure of TBI. We found consistent distributions of normative data and high test-retest reliability. Based on these assessments, we defined a composite score that distinguishes TBI from non-TBI individuals with high sensitivity (83%) and specificity (87%). We conclude that our testing application provides a rapid, portable testing method for TBI.

According to conservative estimates, the country spends a minimum of $25,500-$26,000 per year on each person incarcerated [1]. Incarceration also has long-term costs for both offenders and society. For example, a young person with a prison record may be precluded from becoming a citizen who votes, participates in community-building, and contributes to the community.

Many synesthetes experience colors when viewing letters or digits. We document, for the first time, an analogous phenomenon among users of signed languages who showed color synesthesia for fingerspelled letters and signed numerals. Four synesthetes experienced colors when they viewed manual letters and numerals (in two cases, colors were subjectively projected on to the hands). There was a correspondence between the colors experienced for written graphemes and their manual counterparts, suggesting that the development of these two types of synesthesia is interdependent despite the fact that these systems are superficially distinct and rely on different perceptual recognition mechanisms in the brain.

Neuroscientists have long been interested in the origin of synesthetic pairings. Though the choices made by individual synesthetes sometimes appear idiosyncratic, recent work on moderately sized samples (~10-200 subjects) has found that colors associated with letters reflect environmental influences such as color words, letter frequency, and alphabetical order. We analyzed the letter-color matches from a large sample of grapheme-color synesthetes (6588 subjects) from the database at www.synesthete.org, and report several systematic patterns. The set of all 160,000+ color matches across letters appears to sample from the color space in a biased way. Black, white, red, and yellow are strongly overrepresented, while cyan and magenta are almost never chosen. Whether this bias is mediated by linguistics, perception, or physiological constraints is not known. Consistent with prior work, we find strong tendencies for many letters to be associated with particular colors (A -> red), some of which can be interpreted as arising from environmental influences (Y -> yellow). However, color choices are largely independent across letters: knowing the color of one letter carries little information about the color of any other letter. One interpretation is that environmental influences which drive the letter-color matches are present across the population, but operate probabilistically, suggesting that learning is a ubiquitous influence on grapheme-color synesthesia. We also examined the role of visual statistics on the distance between letter-color matches. Consistent with previous reports, measures of ordinality and letter frequency predict color distances when data are averaged across subjects and letters. However, analyses which take into account both subject variation and the fact that color distances between letter pairs are not independent, show very small effect sizes. Our observations support the view that synesthetic pairings are far from random or idiosyncratic. The findings are also consistent with a widespread role of learning in color-grapheme synethesia. Meeting abstract presented at VSS 2016

Functional magnetic resonance imaging (fMRI) is widely used to study brain circuitry in healthy controls and in psychiatry. A major problem of fMRI studies is motion, which affects the quality of images, is a major source of noise, and can confound data if, for example, the experimental groups move differently. Despite continual reminders to experimental subjects about keeping still, however, movement in the scanner remains a problem. The authors hypothesized that showing head movement during a scanning session may help subjects learn how to keep their head still. The authors scanned subjects and displayed in real time a plot of head movement that had three regions. The authors found, in a limited sample, that the improvements were marginal and inconsistent. Thus, they concluded that this strategy, even if likely to work for some people, is probably not sufficiently successful to be implemented at this time.

Traditionally, criminal research on a national scale has relied primarily on the FBI's Uniform Crime Reports (UCR), a tool with several weaknesses: (1) it contains no unique personal identifiers, precluding analysis of re-offense rates, (2) it lacks detail about individual crimes and their outcomes (e.g., number of charges, plea bargains, dispositions, fines, jail sentences), (3) reporting to the UCR is highly variable, so the aggregate statistics cannot be read as a comprehensive picture of crime. An alternative approach to crime record analysis can be pursued by the study of individual court records, housed in hundreds of counties across the United States. However, each jurisdiction employs local laws and sparse, idiosyncratic information management systems, making it prohibitively difficult to compare detailed crime records across time and place.To overcome all these limitations, we have developed the NeuLaw Criminal Record Database (CRD), a rich and growing collection of tens of millions of crime records. The CRD provides an unprecedented level of detail about individual offenders, their crimes, and their interactions with the criminal justice system; additionally, it translates court records into a common framework for cross-jurisdiction comparison. In particular, the database includes anonymized identifiers to enable large-scale exploration of criminal re-offense (recidivism). The CRD is growing monthly; as of this writing it contains 22.5 million records from 1977 to 2014 from Harris County in Texas, New York City, Miami-Dade County in Florida, and the state of New Mexico. The database can enable or enhance many types of research—for example, identification of high-risk offenders, measurement of changes in policing strategies, and quantification of legislative efficacy—thus giving policy makers the best data upon which to base law enforcement decisions.<br>

: Assessments of attractiveness underlie selection and pursuit of potential mates. Previous research has shown that people are sometimes perceived to be more attractive with a brief glimpse, yet there is no explanation for why this effect might exist. Here, participants rated the attractiveness of males and females photographs, viewed in two conditions: once for 225 ms, and once without time constraints. In the former case, attractiveness judgments were on average higher: briefly glimpsed people were judged to be more attractive. This ‘glimpse effect’ was most pronounced when males rated photos of females. We discuss several possible explanations for these results, including the speculation that the brain determines attractiveness based on Bayesian risk, in which attractiveness ratings are upwardly biased by the high cost of missing a potential mate.

Crack cocaine use carries high costs for society, particularly in terms of increased crime. The tools of modern neuroscience may be able to reduce demand by addressing altered brain circuitry of individuals suffering from severe cocaine use disorder. Here, we review several rehabilitative strategies, including pharmacotherapies targeting neurotransmitter systems, immunotherapies that block cocaine from entering the central nervous system, brain stimulation to disrupt abnormal circuit function, and real-time feedback in neuroimaging to allow the strengthening of impulse control. These experimental treatments hold promise for treating severe cocaine use disorder, and such approaches could be employed as an alternative to widespread incarceration. View the complete article in .pdf form here .

Synesthesia is a neurological condition that gives rise to unusual secondary sensations (e.g., reading letters might trigger the experience of colour). Testing the consistency of these sensations over long time intervals is the behavioural gold standard assessment for detecting synesthesia (e.g., Simner, Mulvenna et al., 2006). In 2007 however, Eagleman and colleagues presented an online 'Synesthesia Battery' of tests aimed at identifying synesthesia by assessing consistency but within a single test session. This battery has been widely used but has never been previously validated against conventional long-term retesting, and with a randomly recruited sample from the general population. We recruited 2847 participants to complete The Synesthesia Battery and found the prevalence of grapheme-colour synesthesia in the general population to be 1.2%. This prevalence was in line with previous conventional prevalence estimates based on conventional long-term testing (e.g., Simner, Mulvenna et al., 2006). This reproduction of similar prevalence rates suggests that the Synesthesia Battery is indeed a valid methodology for assessing synesthesia.

A repeated stimulus is judged as briefer than a novel one. It has been suggested that this duration illusion is an example of a more general phenomenon-namely that a more expected stimulus is judged as briefer than a less expected one. To test this hypothesis, we manipulated high-level expectation through the probability of a stimulus sequence, through the regularity of the preceding stimuli in a sequence, or through whether a stimulus violates an overlearned sequence. We found that perceived duration is not reduced by these types of expectation. Repetition of stimuli, on the other hand, consistently reduces perceived duration across our experiments. In addition, the effect of stimulus repetition is constrained to the location of the repeated stimulus. Our findings suggest that estimates of subsecond duration are largely the result of low-level sensory processing.

In this paper we estimate the minimum prevalence of grapheme-color synesthetes with letter-color matches learned from an external stimulus, by analyzing a large sample of English-speaking grapheme-color synesthetes. We find that at least 6% (400/6588 participants) of the total sample learned many of their matches from a widely available colored letter toy. Among those born in the decade after the toy began to be manufactured, the proportion of synesthetes with learned letter-color pairings approaches 15% for some 5-year periods. Among those born 5 years or more before it was manufactured, none have colors learned from the toy. Analysis of the letter-color matching data suggests the only difference between synesthetes with matches to the toy and those without is exposure to the stimulus. These data indicate learning of letter-color pairings from external contingencies can occur in a substantial fraction of synesthetes, and are consistent with the hypothesis that grapheme-color synesthesia is a kind of conditioned mental imagery.

Gait abnormalities, such as shuffling steps, start hesitation, and freezing, are common and often incapacitating symptoms of Parkinson's disease (PD) and other parkinsonian disorders. Pharmacological and surgical approaches have only limited efficacy in treating these gait disorders. Rhythmic auditory stimulation (RAS), such as playing marching music and dance therapy, has been shown to be a safe, inexpensive, and an effective method in improving gait in PD patients. However, RAS that adapts to patients' movements may be more effective than rigid, fixed-tempo RAS used in most studies. In addition to auditory cueing, immersive virtual reality technologies that utilize interactive computer-generated systems through wearable devices are increasingly used for improving brain-body interaction and sensory-motor integration. Using multisensory cues, these therapies may be particularly suitable for the treatment of parkinsonian freezing and other gait disorders. In this review, we examine the affected neurological circuits underlying gait and temporal processing in PD patients and summarize the current studies demonstrating the effects of RAS on improving these gait deficits.

Abnormal interhemispheric functional connectivity correlates with several neurologic and psychiatric conditions, including depression, obsessive-compulsive disorder, schizophrenia, and stroke. Abnormal interhemispheric functional connectivity also correlates with abuse of cannabis and cocaine. In the current report, we evaluated whether tobacco abuse (i.e., cigarette smoking) is associated with altered interhemispheric connectivity. To that end, we examined resting state functional connectivity (RSFC) using magnetic resonance imaging (MRI) in short term tobacco deprived and smoking as usual tobacco smokers, and in non-smoker controls. Additionally, we compared diffusion tensor imaging (DTI) in the same subjects to study differences in white matter. The data reveal a significant increase in interhemispheric functional connectivity in sated tobacco smokers when compared to controls. This difference was larger in frontal regions, and was positively correlated with the average number of cigarettes smoked per day. In addition, we found a negative correlation between the number of DTI streamlines in the genual corpus callosum and the number of cigarettes smoked per day. Taken together, our results implicate changes in interhemispheric functional and anatomical connectivity in current cigarette smokers.

Perceived duration can be influenced by various properties of sensory stimuli. For example, visual stimuli of higher temporal frequency are perceived to last longer than those of lower temporal frequency. How does the brain form a representation of duration when each of two simultaneously presented stimuli influences perceived duration in different way? To answer this question, we investigated the perceived duration of a pair of dynamic visual stimuli of different temporal frequencies in comparison to that of a single visual stimulus of either low or high temporal frequency. We found that the duration representation of simultaneously occurring visual stimuli is best described by weighting the estimates of duration based on each individual stimulus. However, the weighting performance deviates from the prediction of statistically optimal integration. In addition, we provided a Bayesian account to explain a difference in the apparent sensitivity of the psychometric curves introduced by the order in which the two stimuli are displayed in a two-alternative forced-choice task.

This repository contains all the data and code to recreate the analyses in Witthoft, Winawer, and Eagleman (2015). Prevalence of Learned Grapheme-Color Pairings in a Large Online Sample of Synesthesia. PLoS One.

Traditionally, criminal research on a national scale has relied primarily on the FBI's Uniform Crime Reports (UCR), a tool with several weaknesses: (1) it contains no unique personal identifiers, precluding analysis of re-offense rates, (2) it lacks detail about individual crimes and their outcomes (e.g., number of charges, plea bargains, dispositions, fines, jail sentences), (3) reporting to the UCR is highly variable, so the aggregate statistics cannot be read as a comprehensive picture of crime. An alternative approach to crime record analysis can be pursued by the study of individual court records, housed in hundreds of counties across the United States. However, each jurisdiction employs local laws and sparse, idiosyncratic information management systems, making it prohibitively difficult to compare detailed crime records across time and place. To overcome all these limitations, we have developed the NeuLaw Criminal Record Database (NCRD), a rich and growing collection of tens of millions of crime records. The NCRD provides an unprecedented level of detail about individual offenders, their crimes, and their interactions with the criminal justice system; additionally, it translates court records into a common framework for cross-jurisdiction comparison. In particular, the database includes anonymized identifiers to enable large-scale exploration of criminal re-offense (recidivism). The NCRD is growing monthly; as of this writing it contains 22.5 million records from 1977 to 2014 from Harris County in Texas, New York City, Miami-Dade County in Florida, and the state of New Mexico. The database can enable or enhance many types of research—for example, identification of high-risk offenders, measurement of changes in policing strategies, and quantification of legislative efficacy—thus giving policy makers the best data upon which to base law enforcement decisions.

With one procedural change, jurisdictions can save millions of dollars, keep thousands of innocents out of jail, and strengthen their cases against guilty offenders. In most jurisdictions, a police officer arrests and books a defendant, and then files the criminal complaint before a judge. The judge sets bail, and if necessary, appoints defense counsel for the accused. In theory, the judge rejects those arrests that lack sufficient detail or fail to meet the legal elements of the purported crime, and only the complaints that overcome this check are passed to the local prosecutors. In practice, however, it is often administrative clerks who accept arrests. In many jurisdictions, these clerks lack legal training and are ill equipped to evaluate the merits of each case, resulting in deference to the police officer’s on-site decision. Inadequate cases are later dropped by the prosecutors with the disposition of No Action—but only after extensive investigation and usually not before the accused spent one or more nights in detention. In 1973, Harris County, Texas introduced a new method of intake for accused defendants: prosecutors receive a phone call from the police officer at the moment of arrest. The officer explains the circumstances of the arrest, and the prosecutor evaluates whether it meets the required elements of the crime. If satisfied, the prosecutor grants authorization, and only then does the police officer file. We quantify the efficacy of a pre-authorization intake system by comparing arrest records filed in Harris County, TX, Miami-Dade County, FL, and dozens of counties in New Mexico. We find that a pre-authorization intake system costs on average $1.8-2.9 million less per 100,000 residents than the traditional method of arrests that occur before expert legal evaluation of the strengths or weaknesses of the underlying facts of the case.

To investigate whether the legal concept of "corporate personhood" mirrors an inherent similarity in the neural processing of the actions of corporations and people, we measured brain responses to vignettes about corporations and people while participants underwent functional magnetic resonance imaging. We found that anti-social actions of corporations elicited more intense negative emotions and that pro-social actions of people elicited more intense positive emotions. However, the networks underlying the moral decisions about corporations and people are strikingly similar, including regions of the canonical theory of mind network. In analyzing the activity in these networks, we found differences in the emotional processing of these two types of vignettes: neutral actions of corporations showed neural correlates that more closely resembled negative actions than positive actions. Collectively, these findings indicate that our brains understand and analyze the actions of corporations and people very similarly, with a small emotional bias against corporations.

There are 2 million functionally deaf individuals in the United States and an estimated 53 million worldwide. The cochlear implant (CI) is an effective solution for regaining hearing capabilities for certain populations within this group, but not for all. First, CIs are expensive, ranging from $40,000 to $90,000. Second, CIs require invasive surgery. Third, there is low efficacy of late CI implantation in early-onset deaf adults. Given these considerations, millions of deaf individuals would benefit from a hearing replacement that has low cost, does not involve an invasive procedure, and may have a higher efficacy for early-onset deaf adults. To this end, we are developing a low-cost, non-invasive, plasticity-based solution to deliver auditory information to the brain. Specifically, we are developing a “vibratory vest” by which auditory information is captured, digitally processed, and delivered to the skin of the torso using small vibratory motors. The term for such a technique is sensory substitution, and has previously proven successful in allowing those who are blind to have visual experience through the tongue or skin. In this talk, we will present our fully functional, real-time, Bluetooth-operated prototype, and demonstrate our results from several speech perception experiments. Funding for this research is supported by a training fellowship from the Keck Center of Interdisciplinary Bioscience Training of the Gulf Coast Consortia (NIBIB Grant No. 5T32EB006350-05) and the Renz Foundation.

There are at least 2 million functionally deaf individuals in the United States alone and an estimated 53 million worldwide. The cochlear implant (CI) is an effective solution for regaining hearing capabilities for certain populations within this group, but not for all. First, CIs are expensive, ranging from $40,000 to $90,000 depending on the age of the recipient. This places CIs out of economic reach for many. Second, CIs require invasive surgery. Third, there is low efficacy of late CI implantation in early-onset deaf adults. Given these considerations, there are millions of deaf individuals who would benefit from a hearing replacement that has low cost, does not involve an invasive procedure, and may have a higher efficacy for early-onset deaf adults. To this end, we are developing a low-cost, non-invasive, plasticity-based solution to deliver auditory information to the brain. Specifically, we are developing a “vibratory vest” by which auditory information is captured, digitally processed, and delivered to the skin of the torso using small vibratory motors. The term for such a Technologynique is sensory substitution, and has previously proven successful in allowing those who are blind to have visual experience through the tongue or skin. In this poster, we will present our fully functional, real-time, Bluetooth-operated prototype, and demonstrate our results from several speech perception experiments.

Immediate repetition of a stimulus reduces its apparent duration relative to a novel item. Recent work indicates that this may reflect suppressed cortical responses to repeated stimuli, arising from neural adaptation and/or the predictive coding of expected stimuli. This article summarizes recent behavioral and neurobiological studies linking perceived time to the magnitude of cortical responses, including work suggesting that variations in GABA-mediated cortical inhibition may underlie some of the individual differences in time perception. We suggest that the firing of cortical neurons can be modified using simple recurrent networks with time-dependent processes that are modulated by GABA levels. These local networks feed into a core-timing network used to integrate across stimulus inputs/modalities, thereby allowing for the coordination of multiple duration ranges and effector systems.

Communicating science to the public takes time away from busy research careers. So why would you do it? I here offer six reasons. First, we owe that understanding to the people who fund our experiments, the taxpaying public. Second, we can leverage our skills as scientists to inspire critical thinking in public and political dialog. Third, researchers are optimally positioned to stem the flow of scientific misinformation in the media. Fourth, we can explain the ways and the means by which science can (and cannot) improve law and social policy. Fifth, it is incumbent upon us to explain what science is and is not: while it is a way of thinking that upgrades our intuitions, it also comes with a deep understanding of (and tolerance for) uncertainty. Finally, we find ourselves in the pleasurable position of being able to share the raw beauty of the world around us-and in the case of neuroscience, the world inside us. I suggest that scientists are optimally stationed to increase their presence in the public sphere: our training positions us to synthesize large bodies of data, weigh the evidence, and communicate with nuance, sincerity and exactitude.

Synesthesia is a condition in which normal stimuli can trigger anomalous associations. In this study, we exploit synesthesia to understand how the synesthetic experience can be explained by subtle changes in network properties. Of the many forms of synesthesia, we focus on colored sequence synesthesia, a form in which colors are associated with overlearned sequences, such as numbers and letters (graphemes). Previous studies have characterized synesthesia using resting-state connectivity or stimulus-driven analyses, but it remains unclear how network properties change as synesthetes move from one condition to another. To address this gap, we used functional MRI in humans to identify grapheme-specific brain regions, thereby constructing a functional "synesthetic" network. We then explored functional connectivity of color and grapheme regions during a synesthesia-inducing fMRI paradigm involving rest, auditory grapheme stimulation, and audiovisual grapheme stimulation. Using Markov networks to represent direct relationships between regions, we found that synesthetes had more connections during rest and auditory conditions. We then expanded the network space to include 90 anatomical regions, revealing that synesthetes tightly cluster in visual regions, whereas controls cluster in parietal and frontal regions. Together, these results suggest that synesthetes have increased connectivity between grapheme and color regions, and that synesthetes use visual regions to a greater extent than controls when presented with dynamic grapheme stimulation. These data suggest that synesthesia is better characterized by studying global network dynamics than by individual properties of a single brain region.

A popular model for the representation of time in the brain posits the existence of a single, central-clock. In that framework, temporal distortions in perception are explained by contracting or expanding time over a given interval. We here present evidence for an alternative account, one which proposes multiple independent timelines coexisting within the brain and stresses the importance of motor predictions and causal inferences in constructing our temporal representation of the world. Participants judged the simultaneity of a beep and flash coming from a single source at different distances. The beep was always presented at a constant delay after a motor action, while the flash occurred at a variable delay. Independent shifts in the implied timing of the auditory stimulus toward the motor action (but not the visual stimulus) provided evidence against a central-clock model. Additionally, the hypothesis that the time between action and delayed effect is compressed (known as intentional binding) seems unable to explain our results: firstly, because actions and effects can perceptually reverse, and secondly because the recalibration of simultaneity remains even after the participant's intentional actions are no longer present. Contrary to previous reports, we also find that participants are unable to use distance cues to compensate for the relatively slower speed of sound when audio-visual events are presented in depth. When a motor act is used to control the distal event, however, adaptation to the delayed auditory signal occurs and subjective cross-sensory synchrony is maintained. These results support the hypothesis that perceptual timing derives from and is calibrated by our motor interactions with the world.

The slow speed of neural transmission necessitates that cortical visual information from dynamic scenes will lag reality. The "perceiving the present" (PTP) hypothesis suggests that the visual system can mitigate the effect of such delays by spatially warping scenes to look as they will in ~100 ms from now (Changizi, 2001). We here show that the Hering illusion, in which straight lines appear bowed, can be induced by a background of optic flow, consistent with the PTP hypothesis. However, importantly, the bowing direction is the same whether the flow is inward or outward. This suggests that if the warping is meant to counteract latencies, it is accomplished by a simple strategy that is insensitive to motion direction, and that works only under typical (forward-moving) circumstances. We also find that the illusion strengthens with longer pulses of optic flow, demonstrating motion integration over ~80 ms. The illusion is identical whether optic flow precedes or follows the flashing of bars, exposing the spatial warping to be equally postdictive and predictive, i.e., peri-dictive. Additionally, the illusion is diminished by cues which suggest the bars are independent of the background movement. Collectively, our findings are consistent with a role for networks of visual orientation-tuned neurons (e.g., simple cells in primary visual cortex) in spatial warping. We conclude that under the common condition of forward ego-motion, spatial warping counteracts the disadvantage of neural latencies. It is not possible to prove that this is the purpose of spatial warping, but our findings at minimum place constraints on the PTP hypothesis, demonstrating that any spatial warping for the purpose of counteracting neural delays is not a precise, on-the-fly computation, but instead a heuristic achieved by a simple mechanism that succeeds under normal circumstances.

BACKGROUND: Subjective duration is strongly influenced by repetition and novelty, such that an oddball stimulus in a stream of repeated stimuli appears to last longer in duration in comparison. We hypothesize that this duration illusion, called the temporal oddball effect, is a result of the difference in expectation between the oddball and the repeated stimuli. Specifically, we conjecture that the repeated stimuli contract in duration as a result of increased predictability; these duration contractions, we suggest, result from decreased neural response amplitude with repetition, known as repetition suppression. METHODOLOGY/PRINCIPAL FINDINGS: Participants viewed trials consisting of lines presented at a particular orientation (standard stimuli) followed by a line presented at a different orientation (oddball stimulus). We found that the size of the oddball effect correlates with the number of repetitions of the standard stimulus as well as the amount of deviance from the oddball stimulus; both of these results are consistent with a repetition suppression hypothesis. Further, we find that the temporal oddball effect is sensitive to experimental context--that is, the size of the oddball effect for a particular experimental trial is influenced by the range of duration distortions seen in preceding trials. CONCLUSIONS/SIGNIFICANCE: Our data suggest that the repetition-related duration contractions causing the oddball effect are a result of neural repetition suppression. More generally, subjective duration may reflect the prediction error associated with a stimulus and, consequently, the efficiency of encoding that stimulus. Additionally, we emphasize that experimental context effects need to be taken into consideration when designing duration-related tasks.

Several observations suggest that overlearned ordinal categories (e.g., letters, numbers, weekdays, months) are processed differently than non-ordinal categories in the brain. In synesthesia, for example, anomalous perceptual experiences are most often triggered by members of ordinal categories (Rich et al., 2005; Eagleman, 2009). In semantic dementia (SD), the processing of ordinal stimuli appears to be preserved relative to non-ordinal ones (Cappelletti et al., 2001). Moreover, ordinal stimuli often map onto unconscious spatial representations, as observed in the SNARC effect (Dehaene et al., 1993; Fias, 1996). At present, little is known about the neural representation of ordinal categories. Using functional neuroimaging, we show that words in ordinal categories are processed in a fronto-temporo-parietal network biased toward the right hemisphere. This differs from words in non-ordinal categories (such as names of furniture, animals, cars, and fruit), which show an expected bias toward the left hemisphere. Further, we find that increased predictability of stimulus order correlates with smaller regions of BOLD activation, a phenomenon we term prediction suppression. Our results provide new insights into the processing of ordinal stimuli, and suggest a new anatomical framework for understanding the patterns seen in synesthesia, unconscious spatial representation, and SD.

When observers experience a constant delay between their motor actions and sensory feedback, their perception of the temporal order between actions and sensations adapt (Stetson et al., 2006). We present here a novel neural model that can explain temporal order judgments (TOJs) and their recalibration. Our model employs three ubiquitous features of neural systems: (1) information pooling, (2) opponent processing, and (3) synaptic scaling. Specifically, the model proposes that different populations of neurons encode different delays between motor-sensory events, the outputs of these populations feed into rivaling neural populations (encoding "before" and "after"), and the activity difference between these populations determines the perceptual judgment. As a consequence of synaptic scaling of input weights, motor acts which are consistently followed by delayed sensory feedback will cause the network to recalibrate its point of subjective simultaneity. The structure of our model raises the possibility that recalibration of TOJs is a temporal analog to the motion aftereffect (MAE). In other words, identical neural mechanisms may be used to make perceptual determinations about both space and time. Our model captures behavioral recalibration results for different numbers of adapting trials and different adapting delays. In line with predictions of the model, we additionally demonstrate that temporal recalibration can last through time, in analogy to storage of the MAE.

Synaesthesia is a broadly defined neural phenomenon in which stimulation of a sense or concept triggers a second perception not normally associated with the stimulus. For example, letters or numbers may trigger a colour experience, sounds may trigger a taste sensation, or tastes may trigger a feeling of touch. Dozens of forms of synaesthesia have been reported, but the relationship between the different forms has not been studied: is someone with a particular form of synaesthesia likely to possess other types? If so, which ones? As an inroad to illuminating underlying mechanisms, we here examine which different synaesthesia types tend to co-occur. We analyzed reports of the forms of synaesthesia experienced by 19,133 participants who completed the Synaesthesia Battery (Eagleman, Kagan, Nelson, Sagaram, & Sarma, 2007), using correlation analysis, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and multidimensional scaling (MDS). Our analyses converged on the finding of five distinct groupings of synaesthesia forms. We label these coloured sequence synaesthesias (CSSs), coloured music synaesthesias, non-visual sequela synaesthesias, spatial sequence synaesthesia (SSS), and coloured sensation synaesthesias. Collectively, our findings reveal that synaesthesia is an umbrella term that encompasses several distinct groups with independent probabilities of expression, and this may in turn suggest distinct underlying mechanisms and the possibility of different genetic bases.

This article is a commentary on the article ‘Defining synaesthesia’ ().

How does the brain represent the passage of time at the subsecond scale? Although different conceptual models for time perception have been proposed, its neurophysiological basis remains unknown. We took advantage of a visual duration illusion produced by stimulus novelty to link changes in cortical activity in monkeys with distortions of duration perception in humans. We found that human subjects perceived the duration of a subsecond motion pulse with a novel direction longer than a motion pulse with a repeated direction. Recording from monkeys viewing identical motion stimuli but performing a different behavioral task, we found that both the duration and amplitude of the neural response in the middle temporal area of visual cortex were positively correlated with the degree of novelty of the motion direction. In contrast to previous accounts that attribute distortions in duration perception to changes in the speed of a putative internal clock, our results suggest that the known adaptive properties of neural activity in visual cortex contributes to subsecond temporal distortions.

*Why does your foot hit the brake pedal before you are conscious of danger ahead? *Why do you hear your name is mentioned in a conversation that you didn't think you were listening to? *Why is a person whose name begins with J more likely to marry another person whose name begins with J? *Why is it so difficult to keep a secret? *And how is it possible to get angry at yourself: who, exactly, is mad at whom? A thrilling subsurface exploration of the mind and all its contradictions. A NEW YORK TIMES BESTSELLER

Different features of stimuli are processed in the central nervous system at different speeds. However, such neural time differences do not map directly onto perceptual time differences. How the brain accounts for timing disparities to correctly judge the temporal order of events in the world is the temporal binding problem. I weigh physiological data against new psychophysical findings both within and between modalities. The essence of the paradox is that the timing of neural signals appears, at first blush, too variable for the high accuracy of the psychophysical judgments. I marshal data indicating that ∼80 msec is an important duration in perception and make the novel suggestion that this number is directly mirrored in the physiology. In recordings from several areas of the primate visual system, the difference between the slowest and fastest latencies based on luminance contrast is 80 msec. If the rest of the brain wants to time outside stimuli correctly, it must account for the fact that the earliest stages of the visual system spread signals out in time. I suggest that the brain waits for the slowest information to arrive before committing to a percept. This strategy only applies to visual awareness; in contrast, the motor system may form its reactions based on the first incoming spikes.

Abstract This chapter proposes a hypothesis which holds that the subjective duration assigned to a stimulus reflects the magnitude of the neural response to the stimulus. It evaluates whether attention alone can modulate subjective duration or whether the process involves stimulus predictability and the concomitant amplitudes of neural responses. The findings indicate that the subjective duration assigned to a stimulus parallels the magnitude of the neural response to the stimulus and that the explanation for this lies with predictability, not with attention.

In the flash-lag illusion (FLI), a flash aligned with a moving object appears to be offset. Previously, we presented evidence that visual information from ~80 ms after an event can be used by the visual system to attribute a perceptual decision to the time of the event (Eagleman & Sejnowski, 2000, Science, 287: 2036). The attributed position of the moving object is an interpolation of its previous positions, which suggests that the FLI is a spatial illusion. Our framework contrasts with the latency difference (LD) hypothesis, which assumes that a flash takes a longer time to reach awareness than a continuously moving object; this would make the FLI a temporal illusion. A consequence of the LD framework is that a flash and a moving object presented simultaneously will be perceived with illusory temporal order. We tested this prediction and found that, in contrast to the LD hypothesis, subjects do not perceive mis-ordered stimuli, even under the same experimental conditions that produce the FLI. Our framework of spatial interpolation after a perceptual delay explains other, seemingly-unrelated illusions, such as the Frohlich effect. Being clear on whether the visual system suffers temporal vs. spatial difficulties is critical when interpreting the known physiology. Specifically, if the system does not generally exhibit temporal illusions, and yet different stimuli cause neural responses with different latencies, there must be some mechanism for correctly “time-stamping” the onset of different stimuli. We suggest that in order to compensate for the different latencies, the cerebral cortex waits for slower information to arrive before committing to a perceptual decision. In this way, widely varying stimulus-evoked latencies can be reconciled with precise psychophysical temporal detection.

Under continuous lighting, moving stimuli such as ceiling fans and car wheels can sporadically appear to move in the reverse direction-this phenomenon is known as illusory motion reversal (IMR). We have previously suggested that IMR results from the spurious activation of motion detectors tuned for the opposite direction of motion, leading to a rivalry between two possible motion percepts. To determine if this hypothesis is supported by evidence from electrophysiology, we used EEG to directly compare neural signatures in IMR and binocular rivalry (BR), a well-studied form of rivalry. We find that both IMR and BR show large changes in power in the beta range (14-30 Hz) at the time of a perceptual switch. More importantly, during a stable perception, beta power correlates with the probability of a perception. Specifically, beta power associated with veridical motion perception (experienced the majority of the time) is higher than the power during illusory motion perception (experienced a minority of the time). The BR percepts, each 50% probable, are associated with an intermediate beta amplitude. We propose that the amplitude of synchronized beta activity reflects the size of currently active neural coalitions, with less likely percepts associated with smaller coalitions.

The perceived duration of a stimulus can be modulated by novelty and repetition (Pariyadath & Eagleman, 2007, 2008; Eagleman and Pariyadath, 2009). For example, in a repeated presentation of auditory or visual stimuli, an oddball stimulus of equivalent physical duration appears to last longer, a phenomenon known as the oddball effect. We have proposed that this duration illusion is a reflection of the neural phenomenon of repetition suppression – the diminishment of the neural response to a stimulus that is repeated – suggesting that the illusion reflects not a subjective expansion of the oddball, but rather a contraction of the repeated stimuli. In support of this hypothesis, we show that patient populations with impaired repetition responses, such as in schizophrenia, perceive duration illusions differently from healthy controls. We further present neuroimaging data indicating that repetition suppression in stimulus-specific cortical areas influences subjective duration. Results from our lab and several scattered findings in the literature can be compiled to demonstrate that, in general, any stimulus manipulation that increases response magnitude (such as increasing stimulus size, brightness or predictability) leads to a concurrent increase in the perceived duration of the stimulus (Eagleman and Pariyadath, 2009). We propose the novel hypothesis that the experience of duration is a signature of the amount of energy expended in representing a stimulus–that is, the coding efficiency.

Synesthesia is a phenomenon in which stimulation of one sense triggers an experience in another sense. The most common forms produce an automatic perception of color in response to a grapheme or a word, although there are many forms involving various sensory associations with smell, taste, and touch. Synesthesia is thought to occur in at least 1% of the population, and the associations are quantifiable by measuring their consistency within subjects over time. Using data from the online Synesthesia Battery (www.synesthete.org; Eagleman et al, 2007), we have analyzed the forms of synesthesia reported by almost 6,000 synesthetes. Our results indicate that synesthesia forms tend to cluster into five main groups, one of which we term colored sequence synesthesia (CSS). This clustering pattern suggests that synesthetes with one colored sequence (e.g. number-color) are likely to have others (e.g. letter-color, weekday-color, month-color) but unlikely to have a form like music-color. In an effort to elucidate the neural activity underlying CSS, we present neuroimaging data collected while showing synesthetes clips of black and white children's television. Our preliminary data indicate that synesthetes and non-synesthetes process color in anatomically distinct regions. Finally, the genetic mechanisms responsible for synesthesia have been widely debated but remain largely unknown. We present data from our ongoing family linkage analysis, collected from 48 individuals in five large families. Each affected synesthete was verified for CSS using the Synesthesia Battery. Our results implicate a 23MB region on chromosome 16. In sum, we combine data from cluster analyses, neuroimaging studies, and genetic linkage analyses to present a coherent picture of the neural basis of synesthesia, an understanding which will serve as a powerful guide to the normal operations of neural cross-talk and perception.

The perceived brightness of an object depends on the spatial relationships it has with its neighbors (e.g., brightness induction). We examined whether perceived brightness of a briefly flashed object depends on its temporal relationships with its neighbors. Two gray disks were flashed on either side of a fixation point: one flash lasted for 14 ms (‘brief’); the other lasted for 500 ms (‘long’). Observers reported which flash appeared brighter. When the flashes had simultaneous onset against a dark background, subjects report the brief flash dimmer than the long flash, consistent with the Broca-Sulzer effect. However, when the flashes had simultaneous offset, the brief flash now appeared brighter. The perceived brightness of the brief flash increased monotonically and non-linearly with increasing SOA. When the background was made higher luminance than the flashes, results were reversed: now an onset-matched brief flash appeared brighter, an offset-matched brief flash appeared dimmer. When two brief flashes are presented — one aligned with onset, the other with offset of the long flash — a comparison between them bares the same result: the onset-matched flashed is seen as dimmer than the offset-matched flash. Our results suggest that brightness properties of the brief flashes are temporally integrated with the background, and that the integration time window can be shortened by a salient offset signal nearby. Consistent with this explanation, the differential effect was lost when the flashes were isoluminant with a colored background. We present a model of the neural substrate underlying this phenomenon. Further, we ask whether we are aware of certain kinds of brightness changes, or instead only are aware of the result of integrations over these changes. Our results indicate that we are aware of integrations, and that the duration of the integration window may be changed by salient temporal events in neighboring locations in the visual scene.

Cai and Schlag [VSS 2001] demonstrated that a flashed feature of a moving object — say, a translating bar that flashes blue for one frame — is mislocalized to a later point in the trajectory. If the bar changes height as it moves, then the blueness appears to fill the height of a bar further along the trajectory. They suggested the illusion results from asynchronous feature binding (AFB), i.e., the flashed color change is “delayed and assigned to a later occurring bar” [Cai & Cavanagh, VSS 2002]. Our evidence speaks against an AFB explanation, suggesting instead that motion signals drag the position judgments of the feature-flashed bar (causing “feature-flash drag’). To distinguish between the AFB and motion-biasing models, we presented the illusion with fewer apparent-motion stations: the bar completes its trajectory in the same amount of time, but with fewer appearances. Here, the blue bar appears shifted to a location where no bar was presented. This speaks against AFB, which predicts the assignment of blue to a later appearance of the bar. Cai & Cavanagh suggested that positions of the moving object may be interpolated before AFB; however, our alternative hypothesis of motion-biasing may account for more data (ref. Whitney, 2002). Next, Ss counted the number of white bars that appeared after the blue bar. In the AFB model, blueness assigned to a later bar should cause Ss to undercount. However, Ss counted veridically, supporting the motion-biasing model. Lastly, the blue bar is seen at intermediate heights that never actually occurred (also shown by Cai & Cavanagh). We suggest that motion signals may be applied differentially to the individual edges of an object (here, the top and bottom edges of a growing bar move orthogonally to the bar's translation). Instead of asynchronous perception, this illusion may demonstrate the generality of motion biasing and offer a unified explanation for flash-lag and flash-drag effects.

We have previously reported that the perceived brightness of a brief flash depends on its temporal relationships with its neighbors (the Temporal Neighborhood Illusion [Eagleman et al, VSS 2002]). In our experiment, two flashes, identical in luminance, appear on the screen: one lasts for 56 ms (‘brief’), the other for 278 ms (‘long’). When the flashes have simultaneous onset, subjects report that the brief flash looks dimmer than the long flash (the Broca-Sulzer effect). Surprisingly, however, when the flashes have simultaneous offset, the brief flash appears conspicuously (∼30%) brighter (and much brighter than it appears in isolation). Our new experiments suggest that the brightness enhancement of the offset-aligned flash results from a comparison with the long flash. In our model, the offset-aligned flash appears brighter because the visual system commits to a brightness value for the long flash (say, labeling it a ‘10’) — but the associated neural activity fatigues (adapts) through time. When the new (brief) flash subsequently appears, its attendant neural activity, unfatigued, is greater. When the system compares the ratio of activities, it is forced by its previous commitments to label the new flash brighter, say as a ‘13’. This commitment-adaptation-and-comparison model suggests that two independent representations contribute to brightness perception: one based on neural activity (probably firing rate in V1), and another system that labels the object's brightness, irrespective of the neural fatigue that inevitably follows. This second system, which maintains adaptation-blindness and provides computational savings, is here unmasked by the Temporal Neighborhood Illusion.

In stroboscopic conditions, rotating objects may appear to move in the reverse direction. This illusion arises from an asynchrony between illumination frequency and the periodic frequency of stimulus rotation. A seemingly similar phenomenon occurs in constant sunlight, and this has been suggested as evidence that the visual system processes discrete “snapshots” of the outside world. We reasoned that if snapshots indeed are taken of the visual field, then when a rotating drum appears to transiently reverse direction, its mirror image should always appear to reverse direction simultaneously. Contrary to this prediction, we found that when observers viewed two rotating drums, almost all illusory motion reversals occurred in only one drum at a time, not both at once. This result indicates that the motion reversal illusion cannot be explained by snapshots of the visual field, a theory popular since the advent of cinematography. Independent reversal of the two drums is also found when the two images are presented in the same visual hemifield, further ruling out hemisphere-specific snapshots. The frequency distribution of illusory reversal durations approximates a gamma distribution, suggesting perceptual rivalry as a better explanation for illusory motion reversal. In an adaptive motion-opponency system, the activity of motion-sensitive neurons coding for motion in the reverse direction might intermittently drive the perception of motion. EEG and fMRI experiments are underway to determine the neural difference between veridical and illusory motion perception.

Brief events are sometimes perceived to last longer or shorter in duration than others of equal length. For example, if an oddball is presented within a visual train of repeated stimuli, participants report that the oddball appears longer in duration than the repeated stimulus even if they are physically of equal duration. We have hypothesized that subjective duration distortions are a consequence of differential neural responses to repeated versus novel stimuli (Eagleman, 2008; Pariyadath & Eagleman, 2007, 2008). As seen in EEG, fMRI and single-cell electrophysiology, the neural response to a stimulus diminishes with repeated presentation, an effect known as repetition suppression. We have leveraged the effects of repetition on the subjective duration of brief stimuli to develop a new psychophysical paradigm that we term the proliferation effect. When a single letter of the alphabet was serially flashed onto different locations on the screen, several letters appeared to be present on the screen simultaneously due to persistence of vision. Participants' estimates of how many letters they perceived on the screen at any instant of time were significantly lower when the same letter was flashed repeatedly than when different, randomized letters were used for each flash. This result suggests that the persistence of vision contracts for repeated stimuli. Because of their very rapid time scale, these experiments demonstrate that subjective duration can be computed without explicit temporal judgments. Finally, the proliferation effect gives us a rapid, non-invasive tool to test the integrity of repetition suppression in patient populations with repetition deficits such as schizophrenia.

Human temporal order judgments (TOJs) dynamically recalibrate when participants are exposed to a delay between their motor actions and sensory effects. We here present a novel neural model that captures TOJs and their recalibration. This model employs two ubiquitous features of neural systems: synaptic scaling at the single neuron level and opponent processing at the population level. Essentially, the model posits that different populations of neurons encode different delays between motor-sensory or sensory-sensory events, and that these populations feed into opponent processing neurons that employ synaptic scaling. The system uses the difference in activity between populations encoding for ‘before’ or ‘after’ to obtain a decision. As a consequence, if the network's ‘motor acts’ are consistently followed by sensory feedback with a delay, the network will automatically recalibrate to change the perceived point of simultaneity between the action and sensation. Our model suggests that temporal recalibration may be a temporal analogue to the motion aftereffect. We hypothesize that the same neural mechanisms are used to make perceptual determinations about both space and time, depending on the information available in the neural neighborhood in which the module unpacks.

GUIDE 26 (2006), available at http://www.drugabuse.gov/PDF/PODAT_CJ/PODAT_CJ.pdf("In 2002, it was estimated that the cost to society of drug abuse was $180.9 billion . . .a substantial portion of which-$107.8 billion-is associated with drug-related crime, including criminal justice system costs and costs borne by victims of crime.").4. E.g., Alan I. Leshner, Addiction Is a Brain Disease, and It Matters, 278 SCI.45, 45 (1997) ("Dramatic advances over the past two decades in both the neurosciences and the behavioral sciences have revolutionized our understanding of drug abuse and addiction.").5. Nora D. Volkow & Ting-Kai Li, Drug Addiction: The Neurobiology of Behaviour Gone Awry, 5 NATURE REVS.NEUROSCI.963, 963 (2004) ("[R]ecent studies have shown that repeated drug use leads to long-lasting changes in the brain that undermine voluntary control.").6. Id.

第１章 火曜日はどんな色？ 第２章 万華鏡のような世界 第３章 茶色のＩが青になってしまいませんか？ 第４章 耳で見る 第５章 一一月は左上にある 第６章 味覚について 第７章 オーラ・オーガズム・情動 第８章 メタファー・芸術・創造性 第９章 共感覚者の脳のなか 第１０章 これからの問題

Synesthesia is a perceptual condition in which normal sensory stimulation can trigger anomalous sensory experiences. For example, synesthetes may experience colors in response to sounds, tastes in response to words, or smells in response to touch. We here focus on colored sequence synesthesia, in which color experiences are triggered by learned ordinal sequences such as letters, numbers, weekdays and months. Although synesthesia has been noted in the scientific literature for over a century, it is understood only at the level of the phenomenology, and not at the molecular and neural levels. We have performed a linkage analysis to identify the first genetic loci responsible for the increased neural crosstalk underlying colored sequence synesthesia. Our analysis has identified a 23 MB region on chromosome 16 as a putative locus for the trait. Our data provide the first step in understanding neural crosstalk from its molecular basis to its behavioral consequences, opening a new inroad into the understanding of the multisensory brain.

Abstract Synesthesia is a perceptual condition in which normal sensory stimulation can trigger anomalous sensory experiences. For example, synesthetes may experience colors in response to sounds, tastes in response to words, or smells in response to touch. We here focus on colored sequence synesthesia, in which color experiences are triggered by learned ordinal sequences such as letters, numbers, weekdays and months. Although synesthesia has been noted in the scientific literature for over a century, it is understood only at the level of the phenomenology, and not at the molecular and neural levels. We have performed a linkage analysis to identify the first genetic loci responsible for the increased neural crosstalk underlying colored sequence synesthesia. Our analysis has identified a 23 MB region on chromosome 16 as a putative locus for the trait. Our data provide the first step in understanding neural crosstalk from its molecular basis to its behavioral consequences, opening a new inroad into the understanding of the multisensory brain.

Assessing fitness for duty (FFD) typically requires expensive equipment and large time windows. Here we capitalize on basic principles of human time perception to build a portable software package that can quickly and efficiently test for excessive fatigue or traumatic brain injury. Time perception involves a collaboration of many brain areas, and we hypothesize that generalized damage to the brain can be rapidly assessed by subtle disorders in simple timing tasks. We aim to produce an inexpensive, portable device for rapid detection of fatigue or brain injury both in the clinic and on the field.

Perceived duration is conventionally assumed to correspond with objective duration, but a growing literature suggests a more complex picture. For example, repeated stimuli appear briefer in duration than a novel stimulus of equal physical duration. We suggest that such duration illusions appear to parallel the neural phenomenon of repetition suppression, and we marshal evidence for a new hypothesis: the experience of duration is a signature of the amount of energy expended in representing a stimulus, i.e. the coding efficiency. This novel hypothesis offers a unified explanation for almost a dozen illusions in the literature in which subjective duration is modulated by properties of the stimulus such as size, brightness, motion and rate of flicker.

What happens when the brain awaits a signal of uncertain arrival time, as when a sprinter waits for the starting pistol? And what happens just after the starting pistol fires? Using functional magnetic resonance imaging (fMRI), we have discovered a novel correlate of temporal expectations in several brain regions, most prominently in the supplementary motor area (SMA). Contrary to expectations, we found little fMRI activity during the waiting period; however, a large signal appears after the ''go'' signal, the amplitude of which reflects learned expectations about the distribution of possible waiting times. Specifically, the amplitude of the fMRI signal appears to encode a cumulative conditional probability, also known as the cumulative hazard function. The fMRI signal loses its dependence on waiting time in a ''countdown'' condition in which the arrival time of the go cue is known in advance, suggesting that the signal encodes temporal probabilities rather than simply elapsed time. The dependence of the signal on temporal expectation is present in ''no-go'' conditions, demonstrating that the effect is not a consequence of motor output. Finally, the encoding is not dependent on modality, operating in the same manner with auditory or visual signals. This finding extends our understanding of the relationship between temporal expectancy and measurable neural signals.

What happens when the brain awaits a signal of uncertain arrival time, as when a sprinter waits for the starting pistol? And what happens just after the starting pistol fires? Using functional magnetic resonance imaging (fMRI), we have discovered a novel correlate of temporal expectations in several brain regions, most prominently in the supplementary motor area (SMA). Contrary to expectations, we found little fMRI activity during the waiting period; however, a large signal appears after the "go" signal, the amplitude of which reflects learned expectations about the distribution of possible waiting times. Specifically, the amplitude of the fMRI signal appears to encode a cumulative conditional probability, also known as the cumulative hazard function. The fMRI signal loses its dependence on waiting time in a "countdown" condition in which the arrival time of the go cue is known in advance, suggesting that the signal encodes temporal probabilities rather than simply elapsed time. The dependence of the signal on temporal expectation is present in "no-go" conditions, demonstrating that the effect is not a consequence of motor output. Finally, the encoding is not dependent on modality, operating in the same manner with auditory or visual signals. This finding extends our understanding of the relationship between temporal expectancy and measurable neural signals.

Emerging questions at the interface of law and neuroscience challenge several presumptions at the heart of the legal system. For example, under what circumstances is it a legitimate defense to claim that a brain tumor or idiosyncratic neural wiring was responsible for a behavior? Will neuroscience inform sentencing decisions by offering a better prediction of recidivism? Can novel neuroscience technologies be leveraged for new methods of rehabilitation? I will address these questions with a look toward what neuroscience may and many not be able to tell us about criminal behavior within the next decade. I will additionally cover preliminary experimental data from our novel strategy for real-time functional neuroimaging-based rehabilitation, which I will discuss on both scientific and ethical grounds. Finally, I will touch on Baylor College of Medicine’s Initiative on Neuroscience and Law (www.NeuLaw.org), which brings together a unique collaboration of neurobiologists, legal scholars, and policy makers, with the goal of building modern, evidence-based policy.

At once funny, wistful and unsettling, Sum is a dazzling exploration of unexpected afterlives-each presented as a vignette And lengthening of the others death it says on similarity what. This little more you begin to keep on my friends relations colleagues. Eagleman is like the afterlife you spend your cerebellum grows form present. Why from afar she worships, you are fading ties. Delightful hypothetical fables largely whimsical novelty amusing afterlife.

Abstract Although prediction is one of the key tasks of intelligent brains, it often proves impossible in an unpredictably changing world. Hence, brains often decide what happened retrospectively. This framework of postdiction, the opposite of prediction, stands as an alternative or complimentary framework to prediction. I further show how motor-sensory recalibration demonstrates delay compensation at the perceptual level.

BACKGROUND: The Asp Caterpillar, Megalopyge opercularis, is endemic to the southern United States and causes hundreds of human envenomations annually. Envenomation from the spines of the caterpillar causes severe pain, burning, swelling, nausea, abdominal distress, and headache. Despite the high prevalence of envenomations, little is known about the caterpillars, their geographical distribution, and the symptoms they engender. METHODS: We collected and analyzed 188 case reports of asp caterpillar envenomations over a three-year period. RESULTS: The geographical distribution of the caterpillars is confined to the southeast United States, largely in Texas, Louisiana, and Florida. Symptoms of envenomation vary, but typically include burning pain, swelling, nausea, and itching. The peak months of envenomation are July through November, with few cases reported at other times of year. DISCUSSION: This study sheds light on the caterpillars' distribution and the range of symptoms caused in order to aid in diagnosing puss moth caterpillar envenomation.

Neural responses to a repeated stimulus typically diminish, an effect known as repetition suppression. We here demonstrate what appear to be parallel effects of repetition on subjective duration, even when stimuli are presented too rapidly for explicit temporal judgments. When a brief visual stimulus (e.g., a letter, word, object, or face) was serially flashed in different locations, several stimuli appeared to be present simultaneously due to persistence of vision-we term this the Proliferation Effect. Critically, fewer stimuli were perceived to be simultaneously present when the same stimulus was flashed repeatedly than when a different stimulus was used for each flash, indicating that persistence of vision (and hence subjective duration) shrinks for predictable stimuli. These short-timescale experiments demonstrate that subjective durations are computed at a preconscious and implicit level of processing, thereby changing the temporal interpretation of visual scenes. Further, these findings suggest a new, instant diagnostic test for deficits in repetition suppression, such as those found in schizophrenia.

An illusion of reversed motion may occur sporadically while viewing continuous smooth motion. This has been suggested as evidence of discrete temporal sampling by the visual system in analogy to the sampling that generates the wagon-wheel effect on film (D. Purves, J. A. Paydarfar, & T. J. Andrews, 1996; R. VanRullen, L. Reddy, & C. Koch, 2005). In an alternative theory, the illusion is not the result of discrete sampling but instead of perceptual rivalry between appropriately activated and spuriously activated motion detectors (K. A. Kline, A. O. Holcombe, & D. M. Eagleman, 2004, 2006). Results of the current study demonstrate that illusory reversals of two spatially overlapping and orthogonal motions often occur separately, providing evidence against the possibility that illusory motion reversal (IMR) is caused by temporal sampling within a visual region. Further, we find that IMR occurs with non-uniform and non-periodic stimuli-an observation that is not accounted for by the temporal sampling hypothesis. We propose, that a motion aftereffect is superimposed on the moving stimulus, sporadically allowing motion detectors for the reverse direction to dominate perception.

Abstract : The state of warfare over the past several decades has rapidly evolved, requiring an equally agile adaptation by Army forces. One of the most prevalent consequences of warfare is a lack of adequate rest. Soldiers can receive as little as 0-5 hours of sleep per night for the duration of deployments lasting 12-15 months. In those situations for which adequate sleep is not possible, it would be of value for the Army to understand which skills and abilities are most resilient to sleep deprivation, to pinpoint the underlying brain activity changes, and to determine which remote and reliable measures can serve as a surrogate for metrics that are difficult to measure in mobile individuals in a rugged environment. From the projects described in this paper, it has been possible to identify the regions of neural activity, cognitive abilities, and performance and physiological characteristics that are most robustly altered by sleep deprivation, as well as those that remain relatively unaffected. These deliverables will enable Soldiers on the field to maintain decision-making abilities, manage sustained operations, comprehend high rates of data presentation, and augment leadership effectiveness and cognitive flexibility. From these metrics, a model of human performance under sleep deprivation and physical strain is being developed for use in high optempo training. We are also investigating the use of optimized auditory, visual, and tactile cues for improved signaling communication, and for maintaining and renewing concentration to task.

In the flash-lag illusion, a moving object aligned with a flash is perceived to be offset in the direction of motion following the flash. In the "flash-drag" illusion, a flash is mislocalized in the direction of nearby motion. In the "flash-jump" illusion, a transient change in the appearance of a moving object (e.g., color) is mislocalized in the direction of subsequent motion. Finally, in the Frohlich illusion, the starting position of a suddenly appearing moving object is mislocalized in the direction of the subsequent motion. We demonstrate, in a series of experiments, a unified explanation for all these illusions: Perceptual localization is influenced by motion signals collected over approximately 80 ms after a query is triggered. These demonstrations rule out "latency difference" and asynchronous feature binding models, in which objects appear in their real positions but misaligned in time. Instead, the illusions explored here are best understood as biases in localization caused by motion signals. We suggest that motion biasing exists because it allows the visual system to account for neural processing delays by retrospectively "pushing" an object closer to its true physical location, and we propose directions for exploring the neural mechanisms underlying the dynamic updating of location by the activity of motion-sensitive neurons.

Events can sometimes appear longer or shorter in duration than other events of equal length. For example, in a repeated presentation of auditory or visual stimuli, an unexpected object of equivalent duration appears to last longer. Illusions of duration distortion beg an important question of time representation: when durations dilate or contract, does time in general slow down or speed up during that moment? In other words, what entailments do duration distortions have with respect to other timing judgments? We here show that when a sound or visual flicker is presented in conjunction with an unexpected visual stimulus, neither the pitch of the sound nor the frequency of the flicker is affected by the apparent duration dilation. This demonstrates that subjective time in general is not slowed; instead, duration judgments can be manipulated with no concurrent impact on other temporal judgments. Like spatial vision, time perception appears to be underpinned by a collaboration of separate neural mechanisms that usually work in concert but are separable. We further show that the duration dilation of an unexpected stimulus is not enhanced by increasing its saliency, suggesting that the effect is more closely related to prediction violation than enhanced attention. Finally, duration distortions induced by violations of progressive number sequences implicate the involvement of high-level predictability, suggesting the involvement of areas higher than primary visual cortex. We suggest that duration distortions can be understood in terms of repetition suppression, in which neural responses to repeated stimuli are diminished.

Observers commonly report that time seems to have moved in slow motion during a life-threatening event. It is unknown whether this is a function of increased time resolution during the event, or instead an illusion of remembering an emotionally salient event. Using a hand-held device to measure speed of visual perception, participants experienced free fall for 31 m before landing safely in a net. We found no evidence of increased temporal resolution, in apparent conflict with the fact that participants retrospectively estimated their own fall to last 36% longer than others' falls. The duration dilation during a frightening event, and the lack of concomitant increase in temporal resolution, indicate that subjective time is not a single entity that speeds or slows, but instead is composed of separable subcomponents. Our findings suggest that time-slowing is a function of recollection, not perception: a richer encoding of memory may cause a salient event to appear, retrospectively, as though it lasted longer.

*Contributed equally to this work. A class of synaptic learning models – in which presynaptic terminals have access to a weighted sum of the postsynaptic activity – has traditionally been dismissed as biologically unfeasible. This rejection is not surprising under traditional notions of synaptic connectivity, since postsynaptic cell bodies may be far apart, and there are no backwards signals known to sum activity in a terminal-specific manner. However, many synapses in the CNS become specialized by glial cell ensheathment1. We suggest that such ensheathment may force neighboring cellular elements to share a limited resource:extracellular calcium2-4. We propose the novel theory that certain glomeruli are configured so that the instantaneous external calcium concentration will encode the level of spike activity in postsynaptic cells. We concentrate on the specialized glomeruli that exist in the cerebellum at the interface of the mossy fiber and granule cell layers. Here, dendrites from scores of granule cells swirl around a mossy fiber terminal, and the whole structure is tightly ensheathed in an astrocyte5-6. Simulations demonstrate that the calcium concentration is indeed proportional to a sum of postsynaptic activity in the granule cells. We demonstrate that these extracellular calcium changes are interpretable from an information-processing point of view, generating a novel learning rule for control of plasticity at the mossy fiber/granule cell synapse. This learning rule

Abstract Learning is the process of acquiring knowledge, and memory is the retention of knowledge. Both have their roots in the biochemistry and anatomy of the brain, and are commonly studied by investigating the connection between brain cells, the synapse.

Abstract Reinforcement learning is an approach to learning problems that takes account of the interaction of the learner with their reactive environment. Despite its early connections to animal learning, reinforcement learning has been an active field of study in engineering and computer science. New research is now starting to connect reinforcement learning to identifiable biological systems. These connections may well provide direct insights into goal‐directed learning and decision‐making in biological organisms.

R egret is an emotion that accompanies negative outcomes to decisions for which we have been responsible ([ 1 ][1]). Given a choice between two gambles, subjects will experience regret if the unchosen gamble yields a higher reward than the chosen gamble ([ 2 ][2]). Camille et al . ([ 3 ][3])

Traditional psychophysical studies deliver stimuli to a subject at a time of the experimenter's choosing, not the subject's. But critically different results emerge when a participant's motor act is involved — especially as regards the perception of time. We here report results on motor and sensory integration using a novel psychophysics, fMRI, and modeling. Consistent with previous studies, we found that simultaneity judgments for 2 intra-sensory stimuli (e.g., 2 flashes) were more precise than for cross-sensory stimuli (e.g. a flash and a bang). In both cases the window of simultaneity is symmetric: a flash coming within ∼100 ms of a bang — in either order — will be judged simultaneous. But the story changes when motor acts are involved. When participants judged their keypress against flashes, simultaneity judgments were asymmetrical: participants were extremely sensitive to stimuli that preceded their keypress, but called stimuli up to 120 ms after their keypress simultaneous. This finding is consistent with the precision of operant learning mechanisms that are optimized for causality. Next, participants reported how much before or after their keypress a flash occurred. Although these intervals were judged accurately if the flash came from −200 to 0 ms before their keypress, interval determination of a flash from 0 to 120 ms after their keypress was impaired: all intervals in this region were reported to be close to 0 ms. Our psychophysical data can be captured by a model involving neural pooling and opponent-processing. This model also explains what happens during temporal adaptation (e.g., injected delays between action and sensation), which represents a temporal analogue to the motion aftereffect. We thus hypothesize that identical neural mechanisms underlie judgments of both time and space, allowing analogous illusions in both domains. Including motor acts in time perception informs related issues of prediction, prior expectation, and internal models.

After participants adapted to a delay between their keypress and a flash, they experienced the illusory perception the flashes appearing at shorter delays preceded their keypress. When participants perceived these illusory reversals, BOLD signal increased in the dorsal anterior cingulate cortex, as compared to trials in which the participants perceived the veridical timing. This activation suggests conflict between two timing representation in the brain - one which adapts to the delay between action and effect, and one which does not. Other areas activated in this task - including the insula, inferior frontal gyrus and supramarginal gyrus - may be locations involved in time perception. We show that these areas may relate to a new psychophysical finding: humans have poor interval determination between action and effect up to 120 ms after they perform an action. That is, although motor-sensory intervals were judged accurately if the flash came from −200 to 0 ms before their keypress, interval determination of a flash from 0 to 120 ms after their keypress was impaired: all intervals in this region were reported to be close to 0 ms. The onset and offset of this 120 ms period could be shifted by adapting participants to a frequent 100 ms delay between their keypress and a flash. Collectively, these results indicate a plastic mechanism by which organisms can quickly recalibrate motor-sensory timing.

Most of the actions our brains perform on a daily basis, such as perceiving, speaking, and driving a car, require timing on the scale of tens to hundreds of milliseconds. New discoveries in psychophysics, electrophysiology, imaging, and computational modeling are contributing to an emerging picture of how the brain processes, learns, and perceives time.

Although a subjective urge-or intention-to act appears to precede a voluntary action by almost a quarter of a second, neuroscientists have not had a clear picture of the brain activity that underlies this intentional state. In his Perspective, [Eagleman][1] discusses new work ([ Lau et al .][2]) that uses functional magnetic resonance imaging to distinguish brain areas that are activated in response to the intention to move versus the actual movement. [1]: http://www.sciencemag.org/cgi/content/full/303/5661/1144 [2]: http://www.sciencemag.org/cgi/content/short/303/5661/1208

Little is understood about the perceived speeding and slowing of psychological time. Here I propose that the speed of psychological time passage is regulated, at least in part, by sensory feedback prediction errors. In this framework, sensory feedback is compared against predictions, and the difference (i.e., the error) can tell the nervous system whether its perceived speed of the passage of time is flowing too slowly or quickly. Time perception will accordingly speed or slow to minimize prediction errors. In support of this hypothesis, I report a striking new illusion: duration judgments are distorted during slow-motion sequences in movies. Subjects compared the durations of two brief flashes. The flashes were superimposed over movies of natural biological motion (such as a sprinting cheetah). A flash presented during a slow-motion sequence of the movie is erroneously perceived as having an average of 27% shorter duration than an identical flash presented during a normal-speed sequence of the movie. In frame-shuffled, pixel-scrambled, and upside-down versions of the movie, no illusory time-distortion is found; this indicates that the time-distortion illusion only happens when the future positions of the objects in the movie are predictable. In summary, when a dynamic natural scene changes speed, a moving object's positions may be correctly predicted by a forward internal model of Newtonian physics — however, the timing of those positions is no longer predicted correctly. I suggest the nervous system can eliminate these feedback prediction errors with a simple trick: by modifying its estimated speed of the flow of physical time. Such a change is expected to have measurable perceptual consequences, which I suggest are exposed by this novel time-distortion illusion.

If one believes that his action has caused an event, does that change the way he perceives the timing of his action and/or the event? Haggard et al (2002) reported that when subjects voluntarily pressed a key, which was followed by a beep 250 msec later, the keypress was judged to take place later in time, and the beep earlier in time — i.e., the two events seemed closer together (Eagleman & Holcombe, 2002). Further, in a report by Cunningham et al (2001), subjects anecdotally reported that their actions and delayed effects began to seem simultaneous. To further examine temporal attraction between intentional action and effect, we had subjects play a game in which they adapted to a 100ms delay between their keypress and a resultant flash. Occasionally, a computer opponent would cause this same flash in a time window after the subject's keypress, but before the subject's flash was expected to arrive. After adapting to the action-effect delay, Ss often erroneously answered that flashes appearing in this time window actually occurred before they pressed the button. When they played the same game with no inserted delay, this timing illusion disappeared. One hypothesis is that the keypress was judged by Ss to be later in time. Given this, we attempted to replicate the Haggard et al study, and found that subjects reported a beep to indeed happen earlier in the voluntary condition and later in the involuntary condition (average difference 155+−47 msec). However, it is unclear whether all subjects perceived the *keypress* to be pulled later in time. Further, we were surprised to find that several other versions of causality games that we constructed did not show any significant temporal attractin as a result of agency. This indicates that the putative ‘temporal attraction’ between actions and their effects is not straightforward, but might be overridden by stimuli that give more information. We propose a temporal Bayesian model to partially explain our results.

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In the line-motion illusion, a briefly flashed line appears to propagate from the locus of attention, despite being physically presented on the screen all at once. It has been proposed that the illusion reflects low-level visual information processing that occurs faster at the locus of attention (Hikosaka et al 1993 Vision Research 33 1219-1240; Perception 22 517-526). Such an explanation implicitly embeds the assumption that speeding or slowing of neural signals will map directly onto perceptual timing. This 'online' hypothesis presupposes that signals which arrive first are perceived first. However, other evidence suggests that events in a window of time after the disappearance of a visual stimulus can influence the brain's interpretation of that stimulus (Eagleman and Sejnowski 2000 Science 287 2036-2038; 289 1107a; 290 1051a; 2002 Trends in Neuroscience 25 293). If the online hypothesis were true, we should expect that events occurring after the flashing of the line would not change the illusion. Consistent with our hypothesis that awareness is an a posteriori reconstruction, we demonstrate that the perceived direction of illusory line-motion can be reversed by manipulating stimuli after the line has disappeared.

When a flash is aligned with a moving object, subjects perceive the flash to lag behind the moving object. Two different models have been proposed to explain this "flash-lag" effect. In the motion extrapolation model, the visual system extrapolates the location of the moving object to counteract neural propagation delays, whereas in the latency difference model, it is hypothesized that moving objects are processed and perceived more quickly than flashed objects. However, recent psychophysical experiments suggest that neither of these interpretations is feasible (Eagleman & Sejnowski, 2000a, 2000b, 2000c), hypothesizing instead that the visual system uses data from the future of an event before committing to an interpretation. We formalize this idea in terms of the statistical framework of optimal smoothing and show that a model based on smoothing accounts for the shape of psychometric curves from a flash-lag experiment involving random reversals of motion direction. The smoothing model demonstrates how the visual system may enhance perceptual accuracy by relying not only on data from the past but also on data collected from the immediate future of an event.

One Hertz stimulation of afferents for 15 min with constant interstimulus intervals (regular stimulation) can induce long-term depression (LTD) of synaptic strength in the neocortex. However, it is unknown whether natural patterns of low-frequency afferent spike activity induce LTD. Although neurons in the neocortex can fire at overall rates as low as 1 Hz, the intervals between spikes are irregular. This irregular spike activity (and thus, presumably, irregular activation of the synapses of that neuron onto postsynaptic targets) can be approximated by stimulation with Poisson-distributed interstimulus intervals (Poisson stimulation). Therefore, if low-frequency presynaptic spike activity in the intact neocortex is sufficient to induce a generalized LTD of synaptic transmission, then Poisson stimulation, which mimics this spike activity, should induce LTD in slices. We tested this hypothesis by comparing changes in the strength of synapses onto layer 2/3 pyramidal cells induced by regular and Poisson stimulation in slices from adult visual cortex. We find that regular stimulation induces LTD of excitatory synaptic transmission as assessed by field potentials and intracellular postsynaptic potentials (PSPs) with inhibition absent. However, Poisson stimulation does not induce a net LTD of excitatory synaptic transmission. When the PSP contained an inhibitory component, neither Poisson nor regular stimulation induced LTD. We propose that the short bursts of synaptic activity that occur during a Poisson train have potentiating effects that offset the induction of LTD that is favored with regular stimulation. Thus, natural (i.e., irregular) low-frequency activity in the adult neocortex in vivo should not consistently induce LTD.

In the flash-lag illusion, a flash and a moving object in the same location appear to be offset. A series of psychophysical experiments yields data inconsistent with two previously proposed explanations: motion extrapolation (a predictive model) and latency difference (an online model). We propose an alternative in which visual awareness is neither predictive nor online but is postdictive, so that the percept attributed to the time of the flash is a function of events that happen in the approximately 80 milliseconds after the flash. The results here show how interpolation of the past is the only framework of the three models that provides a unified explanation for the flash-lag phenomenon.

Extracellular calcium is critical for many neural functions, including neurotransmission, cell adhesion, and neural plasticity. Experiments have shown that normal neural activity is associated with changes in extracellular calcium, which has motivated recent computational work that employs such fluctuations in an information-bearing role. This possibility suggests that a new style of computing is taking place in the mammalian brain in addition to current 'circuit' models that use only neurons and connections. Previous computational models of rapid external calcium changes used only rough approximations of calcium channel dynamics to compute the expected calcium decrements in the extracellular space. Using realistic calcium channel models, experimentally measured back-propagating action potentials, and a model of the extracellular space, we computed the fluctuations in external calcium that accrue during neural activity. In this realistic setting, we showed that rapid, significant changes in local external calcium can occur when dendrites are invaded by back-propagating spikes, even in the presence of an extracellular calcium buffer. We further showed how different geometric arrangements of calcium channels or dendrites prolong or amplify these fluctuations. Finally, we computed the influence of experimentally measured synaptic input on peridendritic calcium fluctuations. Remarkably, appropriately timed synaptic input can amplify significantly the decrement in external calcium. The model shows that the extracellular space and the calcium channels that access it provide a medium that naturally integrates coincident spike activity from different dendrites that intersect the same tissue volume.