Cognitive impairments in Parkinson's disease (PD) could be explained by a central executive (CE) deficit in A. D. Baddeley's (1986) working memory model. To test this hypothesis, verbal, spatial, and double span tasks were given to 12 medicated PD patients and control participants, with varying recall delays. The double span task was assigned to explore the coordinating and integrating function of the CE, and lengthening the recall delay was expected to implicate more attentional resources. PD patients had lower spans relative to controls in all tasks. However, the more specific implication of the CE was difficult to prove. One reason could be that PD patients were on dopaminergic treatment when tested. To control this effect, 12 PD patients on and off medication were studied in a second experiment using the same tasks. PD patients off medication had lower spans only in the double task; this result underlines the role of dopamine on working memory processes.

This fMRI study aimed to explore the effect of normal aging on word retrieval and generation. The question addressed is whether lexical production decline is determined by a direct mechanism, which concerns the language operations or is rather indirectly induced by a decline of executive functions. Indeed, the main hypothesis was that normal aging does not induce loss of lexical knowledge, but there is only a general slowdown in retrieval mechanisms involved in lexical processing, due to possible decline of the executive functions. We used three tasks (verbal fluency, object naming, and semantic categorization). Two groups of participants were tested (Young, Y and Aged, A), without cognitive and psychiatric impairment and showing similar levels of vocabulary. Neuropsychological testing revealed that older participants had lower executive function scores, longer processing speeds, and tended to have lower verbal fluency scores. Additionally, older participants showed higher scores for verbal automatisms and overlearned information. In terms of behavioral data, older participants performed as accurate as younger adults, but they were significantly slower for the semantic categorization and were less fluent for verbal fluency task. Functional MRI analyses suggested that older adults did not simply activate fewer brain regions involved in word production, but they actually showed an atypical pattern of activation. Significant correlations between the BOLD (Blood Oxygen Level Dependent) signal of aging-related (A > Y) regions and cognitive scores suggested that this atypical pattern of the activation may reveal several compensatory mechanisms (a) to overcome the slowdown in retrieval, due to the decline of executive functions and processing speed and (b) to inhibit verbal automatic processes. The BOLD signal measured in some other aging-dependent regions did not correlate with the behavioral and neuropsychological scores, and the overactivation of these uncorrelated regions would simply reveal dedifferentiation that occurs with aging. Altogether, our results suggest that normal aging is associated with a more difficult access to lexico-semantic operations and representations by a slowdown in executive functions, without any conceptual loss.

Short-term and working memory (WM) capacities are subject to change with ageing, both in normal older adults and in patients with degenerative or non-degenerative neurological disease. Few normative data are available for comparisons of short-term and WM capacities in the verbal, spatial and visual domains. To provide researchers and clinicians with a set of standardised tasks that assess short-term and WM using verbal and visuospatial materials, and to present normative data for that set of tasks. The present study compiled normative French data for three short-term memory tasks (verbal, visual and spatial simple span tasks) and two WM tasks (verbal and spatial complex span tasks) obtained from 445 healthy older adults aged between 55 and 85 years. Our data reveal main effects of age, education level and gender on older adults' short-term and WM performances. Equation-based normalisation can therefore be used to take these factors into account. The results provide a set of cut-off scores for five standardised tasks that can be used to determine the presence of short-term or WM impairment in older adults.

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The parent and teacher forms of the French version of the Behavioral Rating Inventory of Executive Function (BRIEF) were used to evaluate executive function in everyday life in a large sample of healthy children (N = 951) aged between 5 and 18. Several psychometric methods were applied, with a view to providing clinicians with tools for score interpretation. The parent and teacher forms of the BRIEF were acceptably reliable. Demographic variables (such as age and gender) were found to influence the BRIEF scores. Confirmatory factor analysis was then used to test five competing models of the BRIEF's latent structure. Two of these models (a three-factor model and a two-factor model, both based on a nine-scale structure) had a good fit. However, structural invariance with age was only obtained with the two-factor model. The French version of the BRIEF provides a useful measure of everyday executive function and can be recommended for use in clinical research and practice.

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Au cours des 25 dernières années, des arguments croissants ont conduit à favoriser l'idée selon laquelle les perturbations des fonctions exécutives (FE) sont fréquentes en neuropsychologie de l'enfant. Les enjeux cliniques sont considérables, compte tenu du rôle essentiel du développement de ces processus pour les apprentissages, la régulation du comportement et l'intégration des connaissances sociales. Cet article propose, dans une première partie, une réflexion épistémologique sur les FE chez l'enfant, en regard des différents facteurs inhérents à leur étude dans cette population, et dont la complexité et l'intrication expliquent une émergence tardive des travaux. La dynamique développementale, l'absence de consensus théorique, les difficultés de l'évaluation et la notion de plasticité précoce associée à une lecture clinique délicate sont discutées, facteurs déterminants pour appréhender la spécificité de l'approche clinique des FE de l'enfant. Celle-ci est développée dans la seconde partie, qui revient sur l'émergence de la notion de vulnérabilité précoce des réseaux fronto-sous-corticaux en charge des FE, avant d'exposer la symptomatologie clinique qui se dégage de leur atteinte dans les pathologies acquises et neurodéveloppementales. Sur la base des études de groupe et de cas menées dans ces contextes, une synthèse des particularités qui contribuent à fonder une sémiologie dysexécutive propre à l'enfant est envisagée. Mots clés : fonctions exécutives • enfant • lobe frontal • développement

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