Frédéric Joassin

Human gender differences in an emotional visual oddball task: an event-related potentials study.

Pictures from the Ekman and Friesen series were used in an event-related potentials study to define the timing of occurrence of gender differences in the processing of positive (happy) and negative (fear) facial expressions. Ten male and 10 female volunteers were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy or fearful faces amongst a train of standard stimuli (neutral faces). Behavioral results suggest that men and women detected fearful faces more quickly than happy ones. The main result is that the N2b component, functionally considered as an attentional orienting mechanism, was delayed in men for happy stimuli as compared with fearful ones. Gender differences observed in the processing of emotional stimuli could then originate at the attentional level of the information processing system.

When audition alters vision: an event-related potential study of the cross-modal interactions between faces and voices.

Ten healthy volunteers took part in this event-related potential (ERP) study aimed at examining the electrophysiological correlates of the cross-modal audio-visual interactions in an identification task. Participants were confronted either to the simultaneous presentation of previously learned faces and voices (audio-visual condition; AV), either to the separate presentation of faces (visual, V) or voices (auditive, A). As expected, an interference effect of audition on vision was observed at a behavioral level, as the bimodal condition was performed more slowly than the visual condition. At the electrophysiological level, the subtraction (AV - (A + V)) gave prominence to three distinct cerebral activities: (1) a central positive/posterior negative wave around 110 ms, (2) a central negative/posterior positive wave around 170 ms, AND (3) a central positive wave around 270 ms. These data suggest that cross-modal cerebral interactions could be independent of behavioral facilitation or interference effects. Moreover, the implication of unimodal and multisensory convergence regions in these results, as suggested by a source localization analysis, is discussed.

Cerebral effects of binge drinking : respective influences of global alcohol intake and consumption pattern

OBJECTIVE Binge drinking is a major health concern, but its cerebral correlates are still largely unexplored. We aimed at exploring (1) the cognitive step at which these deficits appear and (2) the respective influence of global alcohol intake and specific binge-drinking consumption pattern on this deficit. METHODS On the basis of a screening phase (593 students), 80 participants were selected and distributed in four groups (control non-drinkers, daily drinkers, low and high binge drinkers). Event-related potentials (ERPs) were recorded while performing a simple visual oddball task. RESULTS Binge drinking was associated with massive ERP impairments, starting at the perceptive level (P100/N100 and N170/P2) and spreading through the attentional (N2b/P3a) and decisional (P3b) ones. Moreover, these deficits were linked with global alcohol intake and also with the specific binge-drinking consumption pattern. CONCLUSIONS Binge drinkers presented early and global ERP deficits, affecting basic and high-level cognitive stages. Moreover, we showed that binge drinking is deleterious for the brain because of alcohol consumption per se, and also because of its specific consumption pattern. SIGNIFICANCE The present results show that binge-drinking habits lead to striking brain consequences, particularly because of the repeated alternation between intense intoxications and withdrawal episodes.

Cross-modal interactions between human faces and voices involved in person recognition

Faces and voices are key features of human recognition but the way the brain links them together is still unknown. In this study, we measured brain activity using functional magnetic resonance imaging (fMRI) while participants were recognizing previously learned static faces, voices and voice-static face associations. Using a subtraction method between bimodal and unimodal conditions, we observed that voice-face associations activated both unimodal visual and auditory areas, and specific multimodal regions located in the left angular gyrus and the right hippocampus. Moreover, a functional connectivity analysis confirmed the connectivity of the right hippocampus with the unimodal areas. These findings demonstrate that binding faces and voices rely on a cerebral network sustaining different aspects of integration such as sensory inputs processing, attention and memory.

Dissociation between affective and cognitive empathy in alcoholism : a specific deficit for the emotional dimension.

BACKGROUND Emotional impairments constitute a crucial and widely described dimension of alcoholism, but several affective abilities are still to be thoroughly explored among alcohol-dependent patients. This is particularly true for empathy, which constitutes an essential emotional competence for interpersonal relations and has been shown to be highly impaired in various psychiatric states. The present study aimed at exploring empathic abilities in alcoholism, and notably the hypothesis of a differential deficit between emotional and cognitive empathy. METHODS Empathy abilities were evaluated among 30 recently detoxified inpatients diagnosed with alcohol dependence and 30 paired healthy controls, using highly validated questionnaires (Interpersonal Reactivity Index [J Pers Soc Psychol44:113] and Empathy Quotient [J Autism Dev Disord34:163]). Correlational analyses were performed to evaluate the links between empathy scores and psychopathological measures (i.e., depression, anxiety, interpersonal problems, and alexithymia). RESULTS When psychiatric comorbities are controlled for, alcoholism is not associated with a general empathy deficit, but rather with a dissociated pattern combining impaired emotional empathy and preserved cognitive one. Moreover, this emotional empathy deficit is not associated with depression or anxiety scores, but is negatively correlated with alexithymia and the severity of interpersonal problems. CONCLUSIONS At the theoretical level, this first observation of a specific deficit for emotional empathy in alcoholism, combined with the exact inverse pattern observed in other psychiatric populations, leads to a double-dissociation, which supports the notion that emotional and cognitive empathy are 2 distinct abilities. At the clinical level, this deficit calls for considering emotional empathy rehabilitation as a crucial concern in psychotherapy.

A common right fronto-parietal network for numerosity and duration processing: An fMRI study

Numerosity and duration processing have been modeled by a functional mechanism taking the form of an accumulator working under two different operative modes. Separate investigations of their cerebral substrates have revealed partly similar patterns of activation, mainly in parietal and frontal areas. However, the precise cerebral implementation of the accumulator model within these areas has not yet been directly assessed. In this study, we asked participants to categorize the numerosity of flashed dot sequences or the duration of single dot displays, and we used functional magnetic resonance imaging (fMRI) to examine the common neural correlates of these processes. The results reveal a large right‐lateralized fronto‐parietal network, including the intraparietal sulcus (IPS) and areas in the precentral, middle and superior frontal gyri, which is activated by both numerosity and duration processing. Complementary psychophysiological interaction (PPI) analyses show a functional connectivity between the right IPS and the frontal areas in both tasks, whereas the right IPS was functionally connected to the left IPS and the right precentral area in the numerosity categorization task only. We propose that the right IPS underlies a common magnitude processing system for both numerosity and duration, possibly corresponding to the encoding and accumulation stages of the accumulator model, whereas the frontal areas are involved in subsequent working‐memory storage and decision‐making processes. Hum Brain Mapp, 2011.

Disrupted regulation of social exclusion in alcohol dependence: An fMRI study.

Alcohol-dependence is associated with cognitive and biological alterations, and also with interpersonal impairments. Although overwhelming in clinical settings and involved in relapse, these social impairments have received little attention from researchers. Particularly, brain alterations related to social exclusion have not been explored in alcohol-dependence. Our primary purpose was to determine the neural correlates of social exclusion feelings in this population. In all, 44 participants (22 abstinent alcohol-dependent patients and 22 paired controls) played a virtual game (‘cyberball’) during fMRI recording. They were first included by other players, then excluded, and finally re-included. Brain areas involved in social exclusion were identified and the functional connectivity between these areas was explored using psycho-physiological interactions (PPI). Results showed that while both groups presented dorsal anterior cingulate cortex (dACC) activations during social exclusion, alcohol-dependent participants exhibited increased insula and reduced frontal activations (in ventrolateral prefrontal cortex) as compared with controls. Alcohol-dependence was also associated with persistent dACC and parahippocampal gyrus activations in re-inclusion. PPI analyses showed reduced frontocingulate connectivity during social exclusion in alcohol-dependence. Alcohol-dependence is thus linked with increased activation in areas eliciting social exclusion feelings (dACC–insula), and with impaired ability to inhibit these feelings (indexed by reduced frontal activations). Altered frontal regulation thus appears implied in the interpersonal alterations observed in alcohol-dependence, which seem reinforced by impaired frontocingulate connectivity. This first exploration of the neural correlates of interpersonal problems in alcohol-dependence could initiate the development of a social neuroscience of addictive states.

Association of the distinct visual representations of faces and names: a PET activation study.

A PET study of seven normal individuals was carried out to investigate the neural populations involved in the retrieval of the visual representation of a face when presented with an associated name, and conversely. Face-name associations were studied by means of four experimental matching conditions, including the retrieval of previously learned (1) name-name (NN), (2) face-face (FF), (3) name-face (NF), and (4) face-name (FN) associations, as well as a resting scan with eyes closed. Before PET images acquisition, subjects were presented with 24 unknown face-name associations to encode in 12 male/female couples. During PET scanning, their task was to decide whether the presented pair was a previously learned association. The right fusiform gyrus was strongly activated in FF condition as compared to NN and Rest conditions. However, no specific activations were found for NN condition relative to FF condition. A network of three areas distributed in the left hemisphere, both active in (NF-FF) and (FN-NN) comparisons, was interpreted as the locus of the integration of visual faces and names representations. These three regions were localized in the inferior frontal gyrus (BA 45), the medial frontal gyrus (BA 6) and the supramarginal gyrus of the inferior parietal lobe (BA 40). An interactive model accounting for these results, with BA 40 seen as an amodal binding region, is proposed.

Is two better than one? A cross-modal oddball paradigm reveals greater sensitivity of the P300 to emotional face-voice associations.

OBJECTIVE Studies exploring neurophysiological correlates of main psychiatric disorders have commonly used event-related potentials (ERP) during a visual or an auditory oddball task. The main results concern modulations of the P3b amplitude and/or latency. The present study aims to increase the clinical sensitivity of these P3b modulations by using a more ecological oddball design, using synchronized pairs of audio-visual emotional stimuli. METHOD Two groups of healthy participants, one composed of controls and the other of students displaying anxious and depressive tendencies completed visual, auditory and audio-visual (cross-modal) oddball tasks, in which they had to detect deviant happy and sad stimuli among neutral ones as quickly as possible. Behavioral performance and P3b ERP data were analyzed. RESULTS Subjects displaying anxious and depressive tendencies exhibited lower P3b amplitude than the controls, but only in the cross-modal oddball task. CONCLUSIONS Although the two groups of subjects differed in their levels of co-morbid anxiety and depression, unimodal visual and auditory oddball tasks did not allow us to detect this difference by P3b amplitude modulations, but the cross-modal task did. SIGNIFICANCE These results suggest that a cross-modal oddball design should be used in future studies to increase the sensitivity of the P300 amplitude differences between healthy participants and those with clinical symptoms.

The impact of the stimulus features and task instructions on facial processing in social anxiety: An ERP investigation

Social anxiety has been characterized by an attentional bias towards threatening faces. Electrophysiological studies have demonstrated modulations of cognitive processing from 100 ms after stimulus presentation. However, the impact of the stimulus features and task instructions on facial processing remains unclear. Event-related potentials were recorded while high and low socially anxious individuals performed an adapted Stroop paradigm that included a colour-naming task with non-emotional stimuli, an emotion-naming task (the explicit task) and a colour-naming task (the implicit task) on happy, angry and neutral faces. Whereas the impact of task factors was examined by contrasting an explicit and an implicit emotional task, the effects of perceptual changes on facial processing were explored by including upright and inverted faces. The findings showed an enhanced P1 in social anxiety during the three tasks, without a moderating effect of the type of task or stimulus. These results suggest a global modulation of attentional processing in performance situations.