References of "Bodart, M. J"
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See detailEffect of familiarity on the processing of human faces
Dubois, S; Rossion, B; Schiltz, Christine UL et al

in NeuroImage (1999), 9(3), 278289

Most brain imaging studies on face perception have investigated the processing of unknown faces and addressed mainly the question of specific face processing in the human brain. The goal of this study was ... [more ▼]

Most brain imaging studies on face perception have investigated the processing of unknown faces and addressed mainly the question of specific face processing in the human brain. The goal of this study was to highlight the effects of familiarity on the visual processing of faces. Using [15O]water 3D Positron Emission Tomography, regional cerebral blood flow distribution was measured in 11 human subjects performing an identical task (gender categorization) on both unknown and known faces. Subjects also performed two control tasks (a face recognition task and a visual pattern discrimination task). They were scanned after a training phase using videotapes during which they had been familiarized with and learned to recognize a set of faces. Two major results were obtained. On the one hand, we found bilateral activations of the fusiform gyri in the three face conditions, including the so-called fusiform-face area, a region in the right fusiform gyrus specifically devoted to face processing. This common activation suggests that different cognitive tasks performed on known and unknown faces require the involvement of this fusiform region. On the other hand, specific regional cerebral blood flow changes were related to the processing of known and unknown faces. The left amygdala, a structure involved in implicit learning of visual representations, was activated by the categorization task on unknown faces. The same task on known faces induced a relative decrease of activity in early visual areas. These differences between the two categorization tasks reveal that the human brain processes known and unknown faces differently. [less ▲]

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See detailNeuronal mechanisms of perceptual learning: Changes in human brain activity with training in orientation discrimination
Schiltz, Christine UL; Bodart, M. J; Dubois, S et al

in NeuroImage (1999), 9(1), 46-62

Using 15O-water 3D positron emission tomography, regional cerebral blood flow was measured twice in six human subjects: before and after extensive training in orientation discrimination. In each session ... [more ▼]

Using 15O-water 3D positron emission tomography, regional cerebral blood flow was measured twice in six human subjects: before and after extensive training in orientation discrimination. In each session subjects performed two orientation discrimination tasks, during which they discriminated the orientation of a grating at either the trained or untrained reference orientation, and a control task, during which they detected a randomly textured pattern. By comparing the discrimination to the detection tasks, we observed a main effect of task bilaterally in the posterior occipital cortex, extending into the left posterior fusiform gyrus and the right inferior occipital gyrus, bilaterally in the intraparietal sulcus, as well as in the cerebellum, thalamus, and brainstem. When we compared the activation pattern before and after the training period, all the changes observed were activity decreases. The nonspecific changes, which were not related to the orientation used during the training, were situated in the cerebellum and bilaterally in the extrastriate visual cortex. The orientation-specific changes, on the other hand, were restricted to the striate and extrastriate visual cortex, more precisely the right calcarine sulcus, the left lingual gyrus, the left middle occipital, and the right inferior occipital gyrus. These findings confirm our hypothesis concerning the existence of learning related changes at early levels of visual processing in human adults and suggest that mechanisms resulting in neuronal activity decreases might be involved in the present kind of learning. [less ▲]

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See detailPET study of human voluntary saccadic eye movements in darkness: Effect of task repetition on the activation pattern
Dejardin, S; Dubois, S; Bodart, M. J et al

in European Journal of Neuroscience (1998), 10

Using H2(15)O 3D Positron Emission Tomography (PET), regional cerebral blood flow (rCBF) was measured in six human subjects under two different conditions: at rest and while performing self-paced ... [more ▼]

Using H2(15)O 3D Positron Emission Tomography (PET), regional cerebral blood flow (rCBF) was measured in six human subjects under two different conditions: at rest and while performing self-paced horizontal saccadic eye movements in darkness. These two conditions were repeated four times each. First, the comparison between the four saccadic and four resting conditions was investigated in a group and a single subject analysis. Saccades elicited bilateral rCBF increases in the medial part of the superior frontal gyrus (supplementary eye field), precentral gyrus (frontal eye field), superior parietal lobule, anterior medial part of the occipital lobe involving striate and extrastriate cortex (lingual gyrus and cuneus), and in the right inferior parietal lobule. At the subcortical level, activations were found in the left putamen. These results mainly replicate previous PET findings on saccadic control. Second, the interaction between the experimental conditions and their repetition was examined. When activations throughout repetition of the same saccadic task are compared, the supplementary eye fields show a progressive increase of activation. On the contrary, the activation in the cerebellum, left superior parietal lobule and left occipital cortex progressively decreases during the scanning session. Given the existence of such an interaction, the pattern of activations must be interpreted as a function of task repetition. This may be a factor explaining some apparent mismatch between different studies. [less ▲]

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