Garga Chatterjee

Human face recognition ability is specific and highly heritable

Compared with notable successes in the genetics of basic sensory transduction, progress on the genetics of higher level perception and cognition has been limited. We propose that investigating specific cognitive abilities with well-defined neural substrates, such as face recognition, may yield additional insights. In a twin study of face recognition, we found that the correlation of scores between monozygotic twins (0.70) was more than double the dizygotic twin correlation (0.29), evidence for a high genetic contribution to face recognition ability. Low correlations between face recognition scores and visual and verbal recognition scores indicate that both face recognition ability itself and its genetic basis are largely attributable to face-specific mechanisms. The present results therefore identify an unusual phenomenon: a highly specific cognitive ability that is highly heritable. Our results establish a clear genetic basis for face recognition, opening this intensively studied and socially advantageous cognitive trait to genetic investigation.

Capturing specific abilities as a window into human individuality: the example of face recognition.

Proper characterization of each individuals unique pattern of strengths and weaknesses requires good measures of diverse abilities. Here, we advocate combining our growing understanding of neural and cognitive mechanisms with modern psychometric methods in a renewed effort to capture human individuality through a consideration of specific abilities. We articulate five criteria for the isolation and measurement of specific abilities, then apply these criteria to face recognition. We cleanly dissociate face recognition from more general visual and verbal recognition. This dissociation stretches across ability as well as disability, suggesting that specific developmental face recognition deficits are a special case of a broader specificity that spans the entire spectrum of human face recognition performance. Item-by-item results from 1,471 web-tested participants, included as supplementary information, fuel item analyses, validation, norming, and item response theory (IRT) analyses of our three tests: (a) the widely used Cambridge Face Memory Test (CFMT); (b) an Abstract Art Memory Test (AAMT), and (c) a Verbal Paired-Associates Memory Test (VPMT). The availability of this data set provides a solid foundation for interpreting future scores on these tests. We argue that the allied fields of experimental psychology, cognitive neuroscience, and vision science could fuel the discovery of additional specific abilities to add to face recognition, thereby providing new perspectives on human individuality.

Chronic-stress induced modulation of different states of anxiety-like behavior in female rats.

Stress facilitates emotionality and consolidation of aversive memories in male rodents. In addition, considerable sexual dimorphism has been observed in animal and clinical literature, both in response to stress and predisposition to anxiety disorders thought to be exacerbated by stress. In view of this, we investigated effects of chronic immobilization stress and chronic unpredictable stress on anxiety-like behavior exhibited by female Wistar rats, using the elevated plus-maze. Neither of the stress paradigms employed in this study significantly influenced anxiety, as manifested by similar open-arm exploration in control and treated animals. Previous studies have reported that in males, exposure to elevated plus-maze during an initial trial significantly reduces open-arm exploration in subsequent retesting, an effect attributed to consolidation of aversive experience of the initial exposure. Control female animals, during a second exposure to the maze 72 h after the first trial, displayed a similar shift to a state of enhanced anxiety. Furthermore, exposure to stress did not affect such consolidation of anxiety, as evidenced by similar reduction in open-arm exploration between control and stressed animals during retesting. We conclude that female rats are insensitive to chronic stress in terms of facilitation and consolidation of anxiety.

Development of pattern vision following early and extended blindness

Significance Deprivation of vision during typical age-defined critical periods results in seemingly irreversible changes in neural organization and behavior in animals and humans. We describe visual development in a unique population of patients who were blind during typical critical periods before removal of bilateral cataracts. The rarity of such cases has previously limited empirical investigations of this issue. Surprisingly, we find substantial improvement after sight onset in contrast sensitivity, a basic visual function that has well-understood neural underpinnings. Our results show that the human visual system can retain plasticity beyond critical periods, even after early and extended blindness. Visual plasticity peaks during early critical periods of normal visual development. Studies in animals and humans provide converging evidence that gains in visual function are minimal and deficits are most severe when visual deprivation persists beyond the critical period. Here we demonstrate visual development in a unique sample of patients who experienced extended early-onset blindness (beginning before 1 y of age and lasting 8–17 y) before removal of bilateral cataracts. These patients show surprising improvements in contrast sensitivity, an assay of basic spatial vision. We find that contrast sensitivity development is independent of the age of sight onset and that individual rates of improvement can exceed those exhibited by normally developing infants. These results reveal that the visual system can retain considerable plasticity, even after early blindness that extends beyond critical periods.

Normal facial age and gender perception in developmental prosopagnosia

Developmental prosopagnosia is characterized by a severe deficit in face-identity recognition. Most developmental prosopagnosics do not report deficits of facial age or gender perception. We developed tasks for evaluating facial age and gender processing and used them in the largest group of developmental prosopagnosics (N = 18) tested on facial age and gender perception. Care was taken to ensure that the tests were sufficiently sensitive to subtle deficits and required holistic processing as assessed by strong inversion effects in control subjects. Despite severe facial identity deficits, developmental prosopagnosics largely performed these discriminations comparably to controls. The common descriptor “faceblind” implied by the term prosopagnosia is inaccurate as certain kinds of nonidentity facial information, which we call physiognomic features, are processed well by both prosopagnosics and age-matched controls alike. Normal facial age and gender perception in developmental prosopagnosics is consistent with parallel processing models in the cognitive architecture of face processing.

Groundwater arsenic contamination in the Ganga-Padma-Meghna-Brahmaputra plain of India and Bangladesh.

magnitude of arsenic groundwater contamination, and its related health effects, in the Ganga-MeghnaBrahmaputra (GMB) plain—an area of 569,749 km2, with a population of over 500 million, which largely comprises the flood plains of 3 major river systems that flow through India and Bangladesh. Design: On the basis of our 17-yr–long study thus far, we report herein the magnitude of groundwater arsenic contamination, its health effects, results of our analyses of biological and food samples, and our investigation into sources of arsenic in the GMB plain Setting: The GMB plain includes the following states in India: Uttar Pradesh in the upper and middle Ganga plain, Bihar and Jharkhand in the middle Ganga plain, West Bengal in the lower Ganga plain, and Assam in the upper Brahmaputra plain. The country of Bangladesh is located in the Padma-Meghna-Brahmaputra plain. In a preliminary study,1 we identified arsenic in water samples from hand-operated tubewells in the GMB plain. Levels in excess of 50 ppb (the permissible limit for arsenic in drinking water in India and Bangladesh) were found in samples from 51 villages in 3 arsenic-affected districts of Uttar Pradesh, 202 villages in 6 districts in Bihar, 11 villages in 1 district in Jharkhand, 3,500 villages in 9 (of a total of 18) districts in West Bengal, 2,000 villages in 50 (of a total of 64) districts in Bangladesh, and 17 villages in 2 districts in Assam. Study Populations: Because, over time, new regions of arsenic contamination have been found, affecting additional populations, the characteristics of our study subjects have varied widely. We feel that, even after working for 17 yr in the GMB plain, we have had only a glimpse of the full extent of the problem. Protocol: Thus far, on the GMB plain, we have analyzed 145,000 tubewell water samples from India and 52,000 from Bangladesh for arsenic contamination. In India, 3,781 villages had arsenic levels above 50 ppb and 5,380 villages had levels exceeding 10 ppb; in Bangladesh, the numbers were 2,000 and 2,450, respectively. We also analyzed 12,954 urine samples, 13,560 hair samples, 13,758 nail samples, and 1,300 skin scale samples from inhabitants of the arsenic-affected villages. Groundwater Arsenic Contamination in the Ganga-Padma-

Results of late surgical intervention in children with early-onset bilateral cataracts.

Background Cataracts are a major cause of childhood blindness globally. Although surgically treatable, it is unclear whether children would benefit from such interventions beyond the first few years of life, which are believed to constitute ‘critical’ periods for visual development. Aims To study visual acuity outcomes after late treatment of early-onset cataracts and also to determine whether there are longitudinal changes in postoperative acuity. Methods We identified 53 children with dense cataracts with an onset within the first half-year after birth through a survey of over 20 000 rural children in India. All had accompanying nystagmus and were older than 8 years of age at the time of treatment. They underwent bilateral cataract surgery and intraocular lens implantation. We then assessed their best-corrected visual acuity 6 weeks and 6 months after surgery. Results 48 children from the pool of 53 showed improvement in their visual acuity after surgery. Our longitudinal assessments demonstrated further improvements in visual acuity for the majority of these children proceeding from the 6-week to 6-month assessment. Interestingly, older children in our subject pool did not differ significantly from the younger ones in the extent of improvement they exhibit. Conclusions and relevance Our results demonstrate that not only can significant vision be acquired until late in childhood, but that neural processes underlying even basic aspects of vision like resolution acuity remain malleable until at least adolescence. These data argue for the provision of cataract treatment to all children, irrespective of their age.

Face gender recognition in developmental prosopagnosia: Evidence for holistic processing and use of configural information

Face identification deficits in developmental prosopagnosics (DPs) have been thought to be due to general difficulties with processing configural face information and integrating configural and parts information into a coherent whole (holistic processing). Gender recognition provides a further opportunity to more fully examine this issue as this ability may be intact in DPs and it has been shown to depend on processing configural information and holistic processing in neurotypical individuals. In the present study we first determined that, indeed, gender discrimination performance was similar in DPs and controls. Second, we found that inversion and scrambling (which we propose measures holistic processing and sensitivity to configural information, respectively) produced comparable deficits in DPs and controls, suggesting that both groups use holistic processing and configural information to recognize gender. This indicates that holistic processing and using configural face information are not general impairments in DP and may be more specific to face identity.

Response to Thomas: Is human face recognition ability entirely genetic?

no reliable variation left to attribute to nonfamilial environment, rendering face recognition ability essentially all genetic. Indeed, we agree that our data could be consistent with zero nonfamilial environmental influence. Given that nonfamilial environmental influence is taken as the reliable variation not shared between monozygotic twins, the failure of two reliability estimates—test–retest (0.70) and alternate-forms (0.76) reliabilities—to significantly exceed the 0.70 monozygotic twin correlation (P > 0.20; one-tailed tests) appears to argue against such a nonfamilial environmental influence. We chose to interpret these results cautiously for two reasons. First, it is difficult to rule out downward biases on these two reliability statistics caused by learning effects (test–retest) and nonequivalence between forms (alternate-forms). Second, another reliability statistic robust to such biases—Cronbach’s α, a measure of internal consistency—produced a higher estimate (0.89 in our twin sample) that left significant room for a nonfamilial environmental influence. Internalconsistencyreliabilityis,however,susceptibletoitsown upward bias. Because internal consistency reliability is computed based on data from a single testing session, any factor that stays relatively constant within a session but varies across sessions— possible examples include alertness, motivation, and mood— could inflate internal consistency reliability relative to the monozygotic twin correlation. Why this inflation? Because such a factor contributes signal to internal consistency reliability (by making a person consistently different from others over the course of a single session) but contributes noise to the twin correlation (because twins are, by definition, tested in separate sessions).

Restoring vision through "Project Prakash": the opportunities for merging science and service.

By treating curably blind children in India, “Project Prakash” brings sight to children of different ages, offering insights into how their brains adapt to enable them to see. The projects experience highlights the benefits of merging basic research with societal service.