Sex differences in interhemispheric communication during face identity encoding: evidence from ERPs.

Sex-related hemispheric lateralization and interhemispheric transmission times (IHTTs) were examined in twenty-four participants at the level of the first visual ERP components (P1 and N170) during face identity encoding in a divided visual-field paradigm. While no lateralization-related and sex-related differences were reflected in the P1 characteristics, these two factors modulated the N170. Indeed, N170 amplitudes indicated a right hemisphere (RH) dominance in men (and a more bilateral functioning in women). N170 latencies and the derived IHTTs confirmed the RH advantage in men but showed the reverse asymmetry in women. Altogether, the results of this study suggest a clear asymmetry in men and a more divided work between the hemispheres in women, with a tendency toward a left hemisphere (LH) advantage. Thus, by extending the pattern to the right-sided face processing, our results generalize previous findings from studies using other materials and indicating longer transfers from the specialized to the non-specialized hemisphere, especially in the male brain. Because asymmetries started from the N170 component, the first electrophysiological index of high-level perceptual processing on face representations, they also suggest a functional account for hemispheric lateralization and sex-related differences rather than a structural one.

Identity-expression interaction in face perception: sex, visual field, and psychophysical factors.

We investigated the psychophysical factors underlying the identity-emotion interaction in face perception. Visual field and sex were also taken into account. Participants had to judge whether a probe face, presented in either the left or the right visual field, and a central target face belonging to same person while emotional expression varied (Experiment 1) or to judge whether probe and target faces expressed the same emotion while identity was manipulated (Experiment 2). For accuracy we replicated the mutual facilitation effect between identity and emotion; no sex or hemispheric differences were found. Processing speed measurements, however, showed a lesser degree of interference in women than in men, especially for matching identity when faces expressed different emotions after a left visual presentation probe face. Psychophysical indices can be used to determine whether these effects are perceptual (A') or instead arise at a post-perceptual decision-making stage (B"). The influence of identity on the processing of facial emotion seems to be due to perceptual factors, whereas the influence of emotion changes on identity processing seems to be related to decisional factors. In addition, men seem to be more "conservative" after a LVF/RH probe-face presentation when processing identity. Women seem to benefit from better abilities to extract facial invariant aspects relative to identity.

Repetition and spacing effects on true and false recognition in the DRM paradigm.

With the Deese-Roediger-McDermott (DRM) paradigm, the repetition effect on false memory had never been clarified. More importantly, the spacing effect on false memory was never directly investigated. So, we carried out two experiments to examine these effects on true and false recognition. In experiment 1, participants studied DRM lists which were presented one, three or five times. In experiment 2, we manipulated the repetition mode (massed vs. spaced with a short interval or a long interval) to explore the spacing effect. The results showed that true recognition increased monotonically with list repetition (experiment 1) and repetition spacing (experiment 2). The most striking finding was a similar spacing effect but no repetition effect on false recognition. Thus, these results were principally discussed in the light of the activation-monitoring framework.

[Apathy in frontotemporal dementia and Alzheimer's disease: are there distinct profiles?]. / L'apathie dans la démence frontemporale et la maladie d'Alzheimer : existe-t-il des profils distincts ?

OBJECTIVE: To find out if distinct clinical profiles of apathy can be distinguished in frontotemporal dementia (FTD) and Alzheimer's disease (AD). SUBJECTS: 13 outpatients with the frontal variant of DFT, 36 with AD and 29 control subjects. METHODS: The scores of the Apathy evaluation scale, AES (Marin), filled in by close relatives, were compared to a) cognitives measures, including global ratings (Mini mental state, Dementia rating scale), and specific assessments for memory (Selective reminding test), inhibition (Stroop test) and planification (6 elements); b) affective measures for depression (Montgomery and Asberg, and Hamilton depression rating scales), emotional disturbances (Abrams and Taylor scale, ATS; Depression mood scale, DMS), assessment of valence and intensity of affective reactions by the International affective picture system, IAPS), dimensions of personality (NEO PI-R, Defensive style questionnaire, DSQ); c) functional assessment: Self-maintenance physical scale (ADL) and Instrumental activities of daily living (Lawton), Social activities scale (Katz and Lyerly), and Disability assessment for dementia, DAD. Apathy was also assessed by the Neuropsychiatric Inventory (NPI) and a new tool, the Goal-directed activities scale (GDAS), which allows a quantitative assessment of 32 goal-directed activities and a qualitative evaluation of 4 causal attributions: E = related to external factors; M = disease related; C = affective disturbance related; and D = lack of motivation. RESULTS: A close relationship was found between AES scores and global cognitive deficits in FTD and AD, but only in AD for the memory and executive tests. No relationship was found with the depression scales or dimensions of personality. A significant relationship was found both in FDT and AD with blunted affect as assessed by ATS, but not with direct assessment by the DMS or reactions to the IAPS. Functional activities were closely related to AES scores in all evaluations, except for ADL score in FTD. Causal attributions were mainly related to lack of motivation in FTD (60% of cases according to the patients, and 85% according to the spouses), and both to affective disturbances (respectively in 36 and 48% of cases) and lack of motivation (33% and 45%) in AD. CONCLUSION: No distinct cognitive or emotional profiles of apathy could be found in FTD and AD. Apathy was constant, more severe, and mainly related to lack of motivation in FTD, less constant, less severe in AD, and related both to affective disturbances and lack of motivation.

Sex and hemispheric differences in facial invariants extraction.

This present study investigates sex differences in hemispheric cooperation during a facial identity matching task. The method used was a divided visual field paradigm in which the probe face was neutral or expressive and the target face was always neutral. Probe and target faces were presented both unilaterally and sequentially. A total of 28 right-handed women and 32 right-handed men participated in this study. The results confirm the women's advantage in face recognition and reveal symmetrical interhemispheric cooperation in women only. In men, processing time was faster when the probe face appeared in the left visual field-and encoded by the right hemisphere-and the target in the right visual field-projected to the left hemisphere-compared to the reverse direction. Interestingly, the data also show that women were not influenced by the expression of the probe face when matching identity, whereas men were always faster when the probe face was neutral, like the target, than when it was expressive. These results are discussed in light of Bruce and Young's (1986) model, and in terms of view-dependent and view-independent processes.

Sex differences in face processing: Are women less lateralized and faster than men?

The aim of this study was to determine the influence of sex on hemispheric asymmetry and cooperation in a face recognition task. We used a masked priming paradigm in which the prime stimulus was centrally presented; it could be a bisymmetric face or a hemi-face in which facial information was presented in the left or the right visual field and projected to the right or the left hemisphere. The target stimulus was always a bisymmetric face presented centrally. Faces were selected from Minear and Park's (2004) database. Fifty-two right-handed students (26 men, 26 women) participated in this experiment, in which accuracy (percentage of correct responses) and reaction times (RTs in ms) were measured. Although accuracy data showed that the percentage of correct recognition- when prime and target matched- was equivalent in men and women, men's RTs were longer than women's in all conditions. Accuracy and RTs showed that men are more strongly lateralized than women, with right hemispheric dominance. These results suggest that men are as good at face recognition as women, but there are functional differences in the two sexes. The findings are discussed in terms of functional cerebral networks distributed over both hemispheres and of interhemispheric transmission.

The time course of repetition effects for familiar faces and objects: an ERP study.

Face and object priming has been extensively studied, but less is known about the repetition processes which are specific to each material and those which are common to both types of material. In order to track the time course of these repetition processes, EEG was recorded while 12 healthy young subjects performed a long-term perceptual repetition priming task using faces and object drawings. Item repetition induced early (N170) and late (P300 and 400-600 ms time-window) event-related potential (ERP) modulations. The N170 component was reduced in response to primed stimuli even with several hundred intervening items and this repetition effect was larger for objects than for faces. This early repetition effect may reflect the implicit retrieval of perceptual features. The late repetition effects showed enhanced positivity for primed items at centro-parietal, central and frontal sites. During this later time-window (400 and 600 ms at central and frontal sites), ERP repetition effects were more obvious at the left side for objects and at the right side for faces. ERP repetition effects were also larger for famous faces during this time-window. These later repetition effects may reflect deeper semantic processing and/or greater involvement of involuntary explicit retrieval processes for the famous faces. Taken together, these results suggest that among the implicit and explicit memory processes elicited by a perceptual priming task, some of them are modulated by the type of item which is repeated.

Impaired facial expression recognition in children with temporal lobe epilepsy: impact of early seizure onset on fear recognition.

The amygdala has been implicated in the recognition of facial emotions, especially fearful expressions, in adults with early-onset right temporal lobe epilepsy (TLE). The present study investigates the recognition of facial emotions in children and adolescents, 8-16 years old, with epilepsy. Twenty-nine subjects had TLE (13 right, 16 left) and eight had fronto-central epilepsy (FCE). Each was matched on age and gender with a control subject. Subjects were asked to label the emotions expressed in pictures of children's faces miming five basic emotions (happiness, sadness, fear, disgust and anger) or neutrality (no emotion). All groups of children with epilepsy performed less well than controls. Patterns of impairment differed according to the topography of the epilepsy: the left-TLE (LTLE) group was impaired in recognizing fear and neutrality, the right-TLE (RTLE) group was impaired in recognizing disgust and, the FCE group was impaired in recognizing happiness. We clearly demonstrated that early seizure onset is associated with poor recognition of facial expression of emotion in TLE group, particularly for fear. Although right-TLE and left-TLE subjects were both impaired in the recognition of facial emotion, their psychosocial adjustment, as measured by the CBCL questionnaire [Achenbach, T. M. (1991). Manual for the Child Behavior Checklist and Youth Self-report. Burlington, VT: University of Vermont Department of Psychiatry], showed that poor recognition of fearful expressions was related to behavioral disorders only in children with right-TLE. Our study demonstrates for the first time that early-onset TLE can compromise the development of recognizing facial expressions of emotion in children and adolescents and suggests a link between impaired fear recognition and behavioral disorders.

The effects of inversion and eye displacements of familiar and unknown faces on early and late-stage ERPs.

OBJECTIVES: The objective of this study is to examine whether configural alterations of faces affect early or late processing stages as a function of their familiarity and their level of representation in memory. We then sought to verify whether the structural encoding stage is susceptible to top-down influences. METHODS: Electrophysiologic and behavioral studies were undertaken, during which unknown and familiar faces were presented upright or upside-down with or without feature alterations. The subjects were asked to determine whether the faces were familiar or not. RESULTS: N170 and N360 amplitudes were larger for familiar faces as well as altered ones. A higher degree of familiarity decreased reaction times (RTs) and N360 latencies, but increased N170 latencies, whereas face alterations increased RTs and latencies of both components examined. However, familiarity interacted with altered face configurations only for RTs and the N170. SIGNIFICANCE: In the perceptual stage, familiar faces seem to develop a more elaborate type of processing because of top-down influences linked to the robust nature of their representations in memory. The more elaborate type of processing for familiar faces has advantageous consequences for the following steps of information processing, by facilitating access to structural representations in memory (N360) as well as the final step reflected by RTs. The fact that configural alterations cause different effects for familiar as opposed to unfamiliar faces indicate that these stimuli are processed in a qualitatively different manner and solicit different representations in memory.

Electrophysiological correlates of facial decision: insights from upright and upside-down Mooney-face perception.

We investigated the ERP correlates of the subjective perception of upright and upside-down ambiguous pictures as faces using two-tone Mooney stimuli in an explicit facial decision task (deciding whether a face is perceived or not in the display). The difficulty in perceiving upside-down Mooneys as faces was reflected by both lower rates of "Face" responses and delayed "Face" reaction times for upside-down relative to upright stimuli. The N170 was larger for the stimuli reported as "faces". It was also larger for the upright than the upside-down stimuli only when they were reported as faces. Furthermore, facial decision as well as stimulus orientation effects spread from 140-190 ms to 390-440 ms. The behavioural delay in 'Face' responses to upside-down stimuli was reflected in ERPs by later effect of facial decision for upside-down relative to upright Mooneys over occipito-temporal electrodes. Moreover, an orientation effect was observed only for the stimuli reported as faces; it yielded a marked hemispheric asymmetry, lasting from 140-190 ms to 390-440 ms post-stimulus onset in the left hemisphere and from 340-390 to 390-440 ms only in the right hemisphere. Taken together, the results supported a preferential involvement of the right hemisphere in the detection of faces, whatever their orientation. By contrast, the early orientation effect in the left hemisphere suggested that upside-down Mooney stimuli were processed as non face objects until facial decision was reached in this hemisphere. The present data show that face perception involves not only spatially but also temporally distributed activities in occipito-temporal regions.

Age-related changes in brain responses to personally known faces: an event-related potential (ERP) study in humans.

Midlife period has not been investigated so far regarding associations between brain responses and spared abilities for face processing. This study examines the effects of midlife aging on behavioural performance and event-related potentials (ERPs) during the perception of personally known faces. Ten middle-aged adults (aged 45-60) and 12 young adults (aged 20-30) performed a visual discrimination task based on the detection of modified eye colours. We found that this task was performed as accurately by middle-aged as by young adults. However, midlife aging is associated with specific ERP latency delays and important changes in scalp ERP distribution. These results -interpreted according to a compensation hypothesis- provide enlightening indications showing that, compared to young adults, the changes in brain activities observed in middle-aged adults may contribute to their maintained behavioural performance.