Etude des substrats cérébraux du fonctionnement exécutif au moyen de l'imagerie cérébrale

Scientific conference (2002, June)

A PET investigation of lexicality and phonotactic frequency in oral language processing

in Cognitive Neuropsychology (2002), 19(4), 343-360

Lexicality and phonotactic frequency effects are observed in many cognitive studies on language processing, but little is known about their underlying neural substrates, especially with regard to ... [more ▼]

Lexicality and phonotactic frequency effects are observed in many cognitive studies on language processing, but little is known about their underlying neural substrates, especially with regard to phonotactic frequency effects. Here, we conducted a positron emission tomography (PET) study in which 11 right-handed volunteers had either to repeat or to listen to lists of words, high phonotactic frequency nonwords, and low phonotactic frequency nonwords. The comparison of word versus nonword processing consistently confirmed previous findings of left temporal and prefrontal activations classically ascribed to lexicosemantic processing. Higher activation was found in the right posterior superior temporal gyrus when comparing high phonotactic frequency nonwords to words, but not when comparing low phonotactic frequency nonwords to words. We propose that this region is implicated in the formation of temporary phonological representations for high-probability phonological events, which may support processing of high phonotactic frequency nonwords [less ▲]

Exploration des fonctions exécutives par imagerie cérébrale

Scientific conference (2002, May)

Brain imaging of the central executive component of working memory

in Neuroscience & Biobehavioral Reviews (2002), 26(2), 105-125

This review presents neuroimaging studies which have explored the cerebral substrates of the central executive component of the working memory model proposed by Baddeley and Hitch [working memory (1986 ... [more ▼]

This review presents neuroimaging studies which have explored the cerebral substrates of the central executive component of the working memory model proposed by Baddeley and Hitch [working memory (1986); Recent advances in learning and motivation (1974)]. These studies have demonstrated that different executive functions (manipulating and updating of information, dual-task coordination, inhibition and shifting processes) not only recruit various frontal areas, but also depend upon posterior (mainly parietal) regions. Such results are in agreement with the hypothesis that executive functions rely on a distributed cerebral network not restricted to anterior cerebral areas. Moreover, the intervention of similar prefrontal regions in a large number of executive tasks suggests that the central executive functioning must be understood in terms of different interactions between a network of regions rather than in terms of a specific association between one region and one higher-level cognitive process [less ▲]

Processus attentionnels et vieillissement normal

in Couillet, Josettte; Leclerq, Michel; Moroni, Christine (Eds.) et al Neuropsychologie de l'attention (2002)

De très nombreuses études ont mis en évidence une diminution de performance des sujets âgés dans une grande variété de tâches cognitives, à la fois en condition de laboratoire et dans la vie réelle ... [more ▼]

De très nombreuses études ont mis en évidence une diminution de performance des sujets âgés dans une grande variété de tâches cognitives, à la fois en condition de laboratoire et dans la vie réelle. Cependant, ce déclin lié à l'âge n'est pas observé dans toutes les situations et les personnes âgées peuvent même présenter dans certaines tâches des performances supérieures à celles des sujets jeunes. [less ▲]

Frontal hypometabolism does not explain inhibitory dysfunction in Alzheimer disease

in Alzheimer Disease and Associated Disorders (2002), 16(4, Oct-Dec), 228-238

A series of tasks assessing inhibitory processes was administered to patients with Alzheimer disease and control subjects. Two groups of patients with Alzheimer disease were examined: patients with ... [more ▼]

A series of tasks assessing inhibitory processes was administered to patients with Alzheimer disease and control subjects. Two groups of patients with Alzheimer disease were examined: patients with hypometabolism restricted to the posterior (temporal and parietal) cerebral areas and patients with hypometabolism in both posterior and anterior (frontal) cerebral areas. The performances of the patients with Alzheimer disease were inferior to those of control subjects on all inhibitory tasks, but the two groups of patients obtained similar scores. These data indicate that frontal lobe hypometabolism is not necessary to produce inhibitory impairment in Alzheimer disease. Consequently, inhibitory dysfunction could be the consequence of a (partial) disconnection process between posterior and anterior cerebral areas. [less ▲]

Inhibition et lobes frontaux

in Boujon, C. (Ed.) L'inhibition au carrefour des neurosciences et des sciences de la cognition : fonctionnements normal et pathologique (2002)

Attention disorders in neurodegenerative diseases

in Leclerq, M.; Zimmerman, P. (Eds.) Applied neuropsychology of attention : theory, diagnosis and rehabilitation (2002)

A number of neuropsychological studies in recent years have shown that demented patients do not necessarily present a global deterioration and that the disease can impair some cognitive processes or ... [more ▼]

A number of neuropsychological studies in recent years have shown that demented patients do not necessarily present a global deterioration and that the disease can impair some cognitive processes or systems, while sparing others. Moreover, qualitatively different patterns of cognitive impairment have been identified in association with different types of neurodegenerative dementias, such as Alzheimer's disease, Huntington's disease, Parkinson's disease or frontotemporal dementia. [less ▲]

Attention et Alzheimer

Scientific conference (2001, December)

Mapping the updating process: conjunctive brain activation across different versions of the running span task

Conference (2001, November)