Receptive fields for flexible face categorizations

Abstract-Examining the receptive fields of brain signals can elucidate how information impinging on the former modulates the latter. We applied this time-honored approach in early vision to the higher-level brain processes underlying face categorizations. Electroencephalograms in response to face-information samples were recorded while observers resolved two different categorizations (gender, expressive or not). Using a method with low bias and low variance, we compared, in a common space of information states, the information determining behavior (accuracy and reaction time) with the information that modulates emergent brain signals associated with early face encoding and later category decision. Our results provide a time line for face processing in which selective attention to diagnostic information for categorizing stimuli (the eyes and their second-order relationships in gender categorization; the mouth in expressive-or-not categorization) correlates with late electrophysiological (P300) activity, whereas early face-sensitive occipito-temporal (N170) activity is mainly driven by the contralateral eye, irrespective of the categorization task.     

Postextinction infusion of a mitogen-activated protein kinase inhibitor into the medial prefrontal cortex impairs memory of the extinction of conditioned fear

We investigated whether postextinction training infusion of PD098059, a selective inhibitor of mitogen-activated protein kinase (MAPK) activation, into the medial prefrontal cortex, would impair retention of extinction learning in rats. We found that immediate, but not late (2 or 4 h), postextinction infusion of PD098059 provoked a full return of conditioned freezing. These results suggest that activation of prefrontal MAPK in early stages of postextinction training participates in processes that protect against spontaneous recovery of aversive responses.     

Allophonic mode of speech perception in dyslexia

Perceptual discrimination between speech sounds belonging to different phoneme categories is better than that between sounds falling within the same category. This property, known as "categorical perception," is weaker in children affected by dyslexia. Categorical perception develops from the predispositions of newborns for discriminating all potential phoneme categories in the world's languages. Predispositions that are not relevant for phoneme perception in the ambient language are usually deactivated during early childhood. However, the current study shows that dyslexic children maintain a higher sensitivity to phonemic distinctions irrelevant in their linguistic environment. This suggests that dyslexic children use an allophonic mode of speech perception that, although without straightforward consequences for oral communication, has obvious implications for the acquisition of alphabetic writing. Allophonic perception specifically affects the mapping between graphemes and phonemes, contrary to other manifestations of dyslexia, and may be a core deficit.     

Information processing limitations as revealed by temporal discrimination

Information processing limit is a fundamental issue in cognitive psychology. One particular way of studying it is to adopt a temporal span perspective. In this experiment, Weber fractions based on thresholds for duration discrimination are used for adopting this perspective. The results showed that, contrary to the constant predicted by Weber's law, the Weber fraction is larger at 2 than at .2 s. This increase is observed in conditions where inter-trial intervals and cognitive load are manipulated, and is argued to be due to the fact that 2 s is beyond a temporal span limit for processing information.     

Effects of daily events on mood states in major depressive disorder

Major depressive disorder (MDD) is characterized by high negative affect (NA) and low positive affect (PA), but little is known about emotional reactivity in daily life. The authors used experience sampling methodology to investigate changes in NA and PA following minor daily events in MDD compared with healthy participants. Contrary to expectation, MDD participants did not report more frequent negative events, although they did report fewer positive events. Multilevel regression showed that both NA and PA responses to negative events were blunted in the MDD group, whereas responses to positive events were enhanced. NA responses to negative events persisted longer in MDD participants. Depressed participants with a positive family history or longer current episodes showed relatively greater NA responses to negative events.     

Predictable postural perturbation in premotor and motor components of reaction time

The aim of the present experiment was to study the central control of posture and movement coordination. Subjects' task was voluntarily to raise their arms in response to a visual signal, this movement generating an unloading in which the weight of the load (0 gm, 1500 gm, 3000 gm, or 4500 gm) was known in advance. Thus, subjects could predict the postural perturbation generated by the unloading. Analysis showed an effect of the unloading conditions: in the 0-gm and 1500-gm conditions, reaction time (RT) was longer than in the 3000-gm and 4500-gm conditions. This decrease in RT was exclusively due to a reduction of the premotor time, confirming the posturokinetic coordination in the programming processes. The implications of the decrease in premotor time with the increase of the perturbation for the posture/movement coordination strategies are also discussed.     

Emerging self-exploration by 2-month-old infants

Two-month-olds and newborns were tested in a situation where they had the opportunity to experience different auditory consequences of their own oral activity on a dummy pacifier. Modulation of oral activity was scored and analyzed relative to two types of contingent auditory feedback, either analog or non-analog to the effort exerted by the infant on the pacifier. The dummy pacifier was connected to an air pressure transducer for recording of oral action. In two different experimental conditions, each time the infant sucked above a certain pressure threshold they heard a perfectly contingent sound of varying pitch. In one condition, the pitch variation was analog to the pressure applied by the infant on the pacifier (analog condition). In another, the pitch variation was random (non-analog condition). As rationale, a differential modulation of oral activity in these two conditions was construed as indexing some voluntary control and the sense of a causal link between sucking and its auditory consequences, beyond mere temporal contingency detection and response–stimulus association. Results indicated that 2-month-olds showed clear signs of modulation of their oral activity on the pacifier as a function of analog versus non-analog condition. In contrast, newborns did not show any signs of such modulation either between experimental conditions (analog versus non-analog contingent sounds) or between baseline (no contingent sounds condition) and experimental conditions. These observations are interpreted as evidence of self-exploration and the emergence of a sense of self-agency by 2 months of age.     

Comparing Different Approaches for Subtyping Children with Conduct Problems: Callous-Unemotional Traits Only Versus the Multidimensional Psychopathy Construct

The aim of this study was to compare two youth psychopathy models (i.e., callous-unemotional versus multidimensional model) in their ability to predict future and stable conduct problems (CP). At baseline, mothers and fathers of 321 boys and 369 girls (ages 7–12) completed measures that tap callous-unemotional and other psychopathic traits. Parent-reported CP was collected at baseline and at 6- and 12 month follow-ups. Children were assigned to mutually exclusive groups based on their levels of CP and psychopathic traits. Children with CP who manifested callous-unemotional traits (Callous-Unemotional?+?CP) were occasionally at risk for future and stable CP. Yet, across gender, children with CP scoring high on all psychopathic trait dimensions (Psychopathic Personality?+?CP) showed the most robust and highest risk for future and stable CP. Also, Callous-Unemotional?+?CP children, and children who were only high in CP, often were at similar risk for future CP. The findings suggest that the callous-unemotional model is less sufficient than the multidimensional model in predicting future and stable CP. This can be concluded for both boys and girls and calls for more research reconsidering the multidimensional nature of psychopathy for CP subtyping purposes.     

Inhibitory control in number-conservation and class-inclusion tasks: A neo-Piagetian inter-task priming study

We investigated whether success in number-conservation and class-inclusion tasks relies on a general ability to inhibit misleading strategies. Two groups of 10-year-olds performed inter-task priming between computerized versions of class-inclusion and number-conservation tasks (Experiment 1). In one group, the class-inclusion task served as a prime and the number-conservation task as an assessment probe and vice versa in the other group. Response times were shorter in the number-conservation task when performed after the class-inclusion task (and vice versa in the other group) than in control prime-probe sequences in which the primes did not require the inhibition of a misleading strategy. Experiment 2 showed that these inter-task priming effects did not simply reflect that class inclusion and number conservation rely on the reversibility of concrete operations as Piaget would have hypothesized. Taken together the results are consistent with the neo-Piagetian assumption that cognitive development is rooted in both the acquisition of knowledge of incremental complexity and the ability to resist (inhibit) previous knowledge. Critically, the present finding suggests that the inhibitory ability is not domain- or strategy-specific.     

One size does not fit all: face emotion processing impairments in semantic dementia, behavioural-variant frontotemporal dementia and Alzheimer's disease are mediated by distinct cognitive deficits

Patients with frontotemporal dementia (both behavioural variant [bvFTD] and semantic dementia [SD]) as well as those with Alzheimer's disease (AD) show deficits on tests of face emotion processing, yet the mechanisms underlying these deficits have rarely been explored. We compared groups of patients with bvFTD (n = 17), SD (n = 12) or AD (n = 20) to an age- and education-matched group of healthy control subjects (n = 36) on three face emotion processing tasks (Ekman 60, Emotion Matching and Emotion Selection) and found that all three patient groups were similarly impaired. Analyses of covariance employed to partial out the influences of language and perceptual impairments, which frequently co-occur in these patients, provided evidence of different underlying cognitive mechanisms. These analyses revealed that language impairments explained the original poor scores obtained by the SD patients on the Ekman 60 and Emotion Selection tasks, which involve verbal labels. Perceptual deficits contributed to Emotion Matching performance in the bvFTD and AD patients. Importantly, all groups remained impaired on one task or more following these analyses, denoting a primary emotion processing disturbance in these dementia syndromes. These findings highlight the multifactorial nature of emotion processing deficits in patients with dementia.