Early (n170/m170) face-sensitivity despite right lateral occipital brain damage in acquired prosopagnosia.

Compared to objects, pictures of faces elicit a larger early electromagnetic response at occipito-temporal sites on the human scalp, with an onset of 130 ms and a peak at about 170 ms. This N170 face effect is larger in the right than the left hemisphere and has been associated with the early categorization of the stimulus as a face. Here we tested whether this effect can be observed in the absence of some of the visual areas showing a preferential response to faces as typically identified in neuroimaging. Event-related potentials were recorded in response to faces, cars, and their phase-scrambled versions in a well-known brain-damaged case of prosopagnosia (PS). Despite the patient's right inferior occipital gyrus lesion encompassing the most posterior cortical area showing preferential response to faces ("occipital face area"), we identified an early face-sensitive component over the right occipito-temporal hemisphere of the patient that was identified as the N170. A second experiment supported this conclusion, showing the typical N170 increase of latency and amplitude in response to inverted faces. In contrast, there was no N170 in the left hemisphere, where PS has a lesion to the middle fusiform gyrus and shows no evidence of face-preferential response in neuroimaging (no left "fusiform face area"). These results were replicated by a magnetoencephalographic investigation of the patient, disclosing a M170 component only in the right hemisphere. These observations indicate that face-preferential activation in the inferior occipital cortex is not necessary to elicit early visual responses associated with face perception (N170/M170) on the human scalp. These results further suggest that when the right inferior occipital cortex is damaged, the integrity of the middle fusiform gyrus and/or the superior temporal sulcus - two areas showing face-preferential responses in the patient's right hemisphere - might be necessary to generate the N170 effect

Is the rapid adaptation paradigm too rapid? Implications for face and object processing

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.neuroimage.2012.03.065. © 2012. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Rapid adaptation is an adaptation procedure in which adaptors and test stimuli are presented in rapid succession. The current study tested the validity of this method for early ERP components by investigating the specificity of the adaptation effect on the face-sensitive N170 ERP component across multiple test stimuli. Experiments 1 and 2 showed identical response patterns for house and upright face test stimuli using the same adaptor stimuli. The results were also identical to those reported in a previous study using inverted face test stimuli (Nemrodov and Itier, 2011). In Experiment 3 all possible adaptor-test combinations between upright face, house, chair and car stimuli were used and no interaction between adaptor and test category, expected in the case of test-specific adaptation, was found. These results demonstrate that the rapid adaptation paradigm does not produce category-specific adaptation effects around 170-200 ms following test stimulus onset, a necessary condition for the interpretation of adaptation results. These results suggest the rapid categorical adaptation paradigm does not work.103305-1/Canadian Institutes of Health Research89822-1/Canadian Institutes of Health ResearchMOP-89822/Canadian Institutes of Health Researc

Etre parent d'enfant atteint des troubles du spectre de l'autisme : Le stress parental à travers l'analyse interprétative phénoménologique.

International audienceL’objectif de notre étude était de faire partager l’expérience de parents, expériences de vie etd’accompagnement de leur enfant atteint des troubles du spectre de l’autisme, afin decomprendre les facteurs du stress parental tels qu’ils étaient perçus par les parents eux-mêmes.Cette recherche visait à élucider de quels éléments sont constitués le vécu des parents d’enfantsautistes, comment ces parents ont vécu l’expérience de vie suite au diagnostic de leur enfant etcomment ils ont su mettre en place « leur normalité » dans leur vie familiale

L'anxiété et les symptômes dépressifs chez les parents d'enfants atteints de syndrome de Dravet

International audienc

Investigating face-property specific processing in the right OFA

Within the neural face-processing network, the right occipital face area (rOFA) plays a prominent role, and it has been suggested that it receives both feed-forward and re-entrant feedback from other face sensitive areas. Its functional role is less well understood and whether the rOFA is involved in the initial analysis of a face stimulus or in the detailed integration of different face properties remains an open question. The present study investigated the functional role of the rOFA with regard to different face properties (identity, expression, and gaze) using transcranial magnetic stimulation (TMS). Experiment 1 showed that the rOFA integrates information across different face properties: performance for the combined processing of identity and expression decreased after TMS to the rOFA, while no impairment was seen in gaze processing. In Experiment 2 we examined the temporal dynamics of this effect. We pinpointed the impaired integrative computation to 170 ms post stimulus presentation. Together the results suggest that TMS to the rOFA affects the integrative processing of facial identity and expression at a mid-latency processing stage

The activation of visual face memory and explicit face recognition are delayed in developmental prosopagnosia

Individuals with developmental prosopagnosia (DP) are strongly impaired in recognizing faces, but the causes of this deficit are not well understood. We employed event-related brain potentials (ERPs) to study the time-course of neural processes involved in the recognition of previously unfamiliar faces in DPs and in age-matched control participants with normal face recognition abilities. Faces of different individuals were presented sequentially in one of three possible views, and participants had to detect a specific Target Face (“Joe”). EEG was recorded during task performance to Target Faces, Nontarget Faces, or the participants' Own Face (which had to be ignored). The N250 component was measured as a marker of the match between a seen face and a stored representation in visual face memory. The subsequent P600f was measured as an index of attentional processes associated with the conscious awareness and recognition of a particular face. Target Faces elicited reliable N250 and P600f in the DP group, but both of these components emerged later in DPs than in control participants. This shows that the activation of visual face memory for previously unknown learned faces and the subsequent attentional processing and conscious recognition of these faces are delayed in DP. N250 and P600f components to Own Faces did not differ between the two groups, indicating that the processing of long-term familiar faces is less affected in DP. However, P600f components to Own Faces were absent in two participants with DP who failed to recognize their Own Face during the experiment. These results provide new evidence that face recognition deficits in DP may be linked to a delayed activation of visual face memory and explicit identity recognition mechanisms

Facial identity and facial expression are initially integrated at visual perceptual stages of face processing

It is frequently assumed that facial identity and facial expression are analysed in functionally and anatomically distinct streams within the core visual face processing system. To investigate whether expression and identity interact during the visual processing of faces, we employed a sequential matching procedure where participants compared either the identity or the expression of two successively presented faces, and ignored the other irrelevant dimension. Repetitions versus changes of facial identity and expression were varied independently across trials, and event-related potentials (ERPs) were recorded during task performance. Irrelevant facial identity and irrelevant expression both interfered with performance in the expression and identity matching tasks. These symmetrical interference effects show that neither identity nor expression can be selectively ignored during face matching, and suggest that they are not processed independently. N250r components to identity repetitions that reflect identity matching mechanisms in face-selective visual cortex were delayed and attenuated when there was an expression change, demonstrating that facial expression interferes with visual identity matching. These findings provide new evidence for interactions between facial identity and expression within the core visual processing system, and question the hypothesis that these two attributes are processed independently

Normal perception of Mooney faces in developmental prosopagnosia: evidence from the N170 component and rapid neural adaptation

Individuals with developmental prosopagnosia (DP) have a severe difficulty recognizing the faces of known individuals in the absence of any history of neurological damage. These recognition problems may be linked to selective deficits in the holistic/configural processing of faces. We used two-tone Mooney images to study the processing of faces versus non-face objects in DP when it is based on holistic information (or the facial gestalt) in the absence of obvious local cues about facial features. A rapid adaptation procedure was employed for a group of 16 DPs. Naturalistic photographs of upright faces were preceded by upright or inverted Mooney faces or by Mooney houses. DPs showed face-sensitive N170 components in response to Mooney faces versus houses, and N170 amplitude reductions for inverted as compared to upright Mooney faces. They also showed the typical pattern of N170 adaptation effects, with reduced N170 components when upright naturalistic test faces were preceded by upright Mooney faces, demonstrating that the perception of Mooney and naturalistic faces recruits shared neural populations. Our findings demonstrate that individuals with DP can utilize global information about face configurations for categorical discriminations between faces and non-face objects, and suggest that face processing deficits emerge primarily at more fine-grained higher level stages of face perception