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Objective Apraxia is the inability to perform voluntary, skilled movements following brain lesions, in the absence of sensory integration deficits. Yet, patients with neurodegenerative diseases (ND) may have sensory integration deficits, so we tested the associations and dissociations between apraxia and sensory integration. Methods A total of 44 patients with ND and 20 healthy controls underwent extensive testing of sensory integration (i.e., localization of tactile, visual, and proprioceptive stimuli; agraphesthesia; astereognosis) and apraxia (i.e., finger dexterity, imitation, tool use). Results The results showed (i) that patients with Alzheimer’s disease, corticobasal syndrome, or posterior cortical atrophy were impaired on both dimensions; (ii) An association between both dimensions; (iii) that when sensory integration was controlled for, the frequency of apraxia decreased dramatically in some clinical subgroups. Conclusion In a non-negligible portion of patients, the hypothesis of a disruption of sensory integration can be more parsimonious than the hypothesis of apraxia in case of impaired skilled gestures. Clinicians and researchers are advised to integrate sensory integration measures along with their evaluation of apraxia.

Visuo-imitative apraxia has been consistently reported in patients with dementia, yet there have been substantial methodological differences between studies, while multiple, sometimes competing hypotheses have been put forward to explain this syndrome. Our goals were to study specific imitation deficits in groups of patients who have been selected and assigned to a group solely based on clinical criteria. We tested the effects of body part, bimanual imitation, asymmetry of the model, and body midline crossing, in patients with cortical atrophy of the temporal lobes (semantic dementia, SD), frontal-parietal networks (FPN, i.e., posterior cortical atrophy and corticobasal syndrome) or both (Alzheimer's disease, AD). Sixty-three patients and 32 healthy controls were asked to imitate 45 meaningless finger/hand, uni-/bimanual, asymmetrical/symmetrical, and crossed/uncrossed postures. SD patients had subnormal imitation scores. FPN patients showed frequent and marked deficits in most conditions, better performance with hand than finger postures (probably because of visuo-constructive deficits), and better performance with uncrossed than crossed configurations (probably because of body schema disorganization). Bimanual configurations were difficult for AD patients, not because of bimanual activity in itself, but rather because of the complexity of the model. The finding of dissociations in 34/63 cases (54%) suggests that some patients, even within the same clinical category, can have variable performance in imitation tests as a function of the abovementioned factors. Clinicians are advised to use tests with a large array of items to properly capture patients' imitation skills. This provides a new basis for future research to unpack which neurocognitive mechanisms are disrupted to cause specific patterns of impaired imitation.

Les troubles d’utilisation d’outils constituent une plainte frequente en clinique pediatrique, notamment en cas de trouble developpemental de la coordination (TDC), et peuvent limiter la participation de l’enfant aux activites de vie quotidienne. Pourtant, l’absence de theorie explicative consensuelle dans le TDC induit des strategies d’examen peu structurees, voire affranchies de cadrage theorique, qui n’integrent pas automatiquement l’evaluation du retentissement des difficultes dans la vie quotidienne. Cet article propose d’interroger, dans une premiere partie, la nature des troubles gestuels et de coordination motrice chez l’enfant TDC ainsi que leur role eventuel dans l’utilisation d’outils. La pertinence des concepts theoriques et des evaluations cliniques mises en œuvre est egalement questionnee au regard de l’analyse des difficultes d’utilisation. La seconde partie expose les modelisations theoriques formulees dans le developpement typique et en neuropsychologie adulte, susceptibles d’eclairer la comprehension de ces symptomes chez l’enfant TDC. Enfin, les perspectives d’un examen differentiel et theoriquement guide de l’utilisation d’outils chez l’enfant sont abordees a l’issue de cette revue.

International audience; While imitation of meaningless gestures is a gold standard in the assessment of apraxia in patients with either stroke or neurodegen- erative diseases, little is known about potential age-related effects on this measure. A significant body of literature has indicated that different mechanisms (i.e., executive functioning, visuospatial skills, sensory integration, body knowledge, categorical apprehension) may underlie the performance depending on imitation conditions (i.e., finger/hand, uni-/bimanual, symmetric/asymmetric, crossed/ uncrossed configurations). However, neither the effects of these conditions on performance, nor the contribution of the abovemen- tioned mechanisms to imitation have been explored in normal aging. The aim of the present study was to fill this gap. To do so, healthy adults (n = 103) aged 50 to 89 were asked to imitate 45 meaningless gestures. The authors controlled for general cognitive function, motor function, visual-spatial skills, executive function, sensory inte- gration, body knowledge, and mechanical problem-solving skills. The results showed that asymmetry, body-midline crossing and, to a lesser extent, bimanual activity added an additional layer of diffi- culty to imitation tasks. After controlling for motor speed and cogni- tive function, age had an effect on imitation skills after 70 years old. This may reflect a decline in body knowledge, sensory integration, and executive functions. In contrast, the visuospatial and mechanical problem-solving hypotheses were ruled out. An additional motor simulation hypothesis is proposed. These findings may prove useful for clinicians working inmemory clinics by providing insights on how to interpret imitation deficits. Lower performance after 70 years old should not be considered abnormal in a systematic manner.

International audience; We report the case of M.B. who demonstrated severe optic ataxia with the right hand following stroke in the left hemisphere. The clinical picture may shed light on both the pathological characteristics of reaching and grasping actions, and potential rehabilitation strategies for optic ataxia. First, M.B. demonstrated a dissociation between severely impaired reaching and relatively spared grasping and tool use skills and knowledge, which confirms that grasping may be more intermingled with non-motoric cognitive mechanisms than reaching. Besides, M.B.’s reaching performance was sensitive to movement repetition. We observed a substitution effect: Reaching time decreased if M.B. repeatedly reached toward the same object but increased when object identity changed. This may imply that not only object localization but also object identity, is integrated into movement programming in reach-to-grasp tasks. Second, studying M.B.’s spontaneous compensation strategies ascertained that the mere repetition of reaching movements had a positive effect, to the point M.B. almost recovered to normal level after an intensive one-day repetitive training session. This case study seems to provide one of the first examples of optic ataxia rehabilitation. Reaching skills can be trained by repetitive training even two years post-stroke and despite the presence of visuo-imitative apraxia.

International audience; The present study investigated the nature and specificity of the gestural deficit in children with developmental coordination disorder (DCD). Performance of children with DCD is compared with that of typically developing children across tasks and conditions that allow exploring distinct levels hypothesized by adult models of praxis processing. These models generally involve a conceptual system and a production system. Within this theoretical framework, the study analyzed the extent to which the gestural difficulties of children with DCD are related to a deficit of the production system. Considering the heterogeneity of deficits consistently reported in DCD, we also examined whether gestural difficulties of children with DCD could imply impairments on other cognitive functions (executive functions, visual-perceptual, and visuospatial functions). Thirty children with DCD were compared to 30 typically developing children. The DCD group exhibited a deficit in most of the gesture production tasks (with the exception of representational intransitive ones), with impaired visuospatial skills. When controlling for a measure of visuospatial skill, differences between groups remained significant only for representational transitive gestures. This dysfunction could neither be related to a semantic deficit, nor to an impairment of sensorimotor knowledge. Therefore, if the contribution of a visuospatial dysfunction allows discussing the specificity of gestural deficit, this does not appear to explain the overall gestural deficit. We suggest an explanation of the finding within the assumption of a production-system deficit.

International audience; Les 40 ans de la Société de neuropsychologie de langue française sont l'occasion de retracer l'histoire récente du concept d'apraxie. Depuis les travaux de Geschwind dans les années 1970 qui ont largement inspiré les modélisations cognitives encore utilisées aujourd'hui, ces dernières décennies ont vu un nombre important de notions émergées. Cet article a pour objectif de retracer, en sui-vant une logique chronologique, l'émergence et l'évolution des concepts qui se sont donné pour but d'expliquer les troubles praxiques. Parmi ces concepts théoriques, trois ont été particulièrement étudiés : la mémoire sémantique, les engrammes gestuels et les approches basées sur le raisonnement. Si ces courants permettent de fournir un cadre d'analyse inté-ressant aux troubles observés dans la clinique, ils comportent également des limites et ne cessent d'alimenter les débats actuels. Dans une dernière partie, nous proposerons des pistes de réflexion sur les questions qui animent et animeront l'étude de l'apraxie dans les années à venir. Nous aborderons notamment le lien entre apraxie et schéma corporel et le rôle de l'expérience. La nécessité de proposer un cadre théorique cohérent aux difficultés praxiques observées chez l'enfant sera également discutée. Mots clés : apraxie · mémoire sémantique · engrammes gestuels · approche basée sur le raisonnement

International audience; This study aimed at examining motor and ideomotor praxis skills in children with neurofibromatosis type 1 (NF1). The impact of executive dysfunction, frequently described in children with NF1, on the expression of praxis impairments was also studied. Eighteen children with NF1 were included and matched with 20 control children for age (7–14 years), sex, laterality, and parental education level. Both groups of children underwent an assessment based on cognitive models of apraxia including visuomotor tasks, executive tests, and everyday life questionnaires. The group of children with NF1 showed a trend to weaker performances on motor and ideomotor praxis than the control group, only on the finger use condition (ps .08). Moreover, these praxis difficulties disappeared when executive dysfunctions (planning and inhibition) were controlled. These findings support the negative impact of executive dysfunctions on praxis skills in children with NF1. The identification of praxis and executive function disorders as well as their interaction is important for differentiating primary praxic disorder from a cognitive deficit that may be expressed in gesture. Clinically, this distinction is essential to optimize targeted and effective rehabilitative interventions.

Just like all the others specific learning disorders, dyspraxia is a key issue for public health and school performance. “Developmental dyspraxia” qualifies specific disturbances of gesture, i.e. the ability to produce a finalized action (goal-directed movement) and to use the objects [1] , [2] . Even if dyspraxia was described for decades, the value of the concept for diagnosis raises some debates in the international literature. Since 1994, a consensus has been established on the diagnostic entity of Developmental Coordination Disorder (DCD) to describe all children who exhibit developmental deficits of “motor coordination”. Beyond the usual debate of terminology, both the theoretical and the clinical definitions of the gestural dysfunctions in children remain insufficient in various respects. This communication provides a review of current controversies regarding the field of dyspraxia and DCD. Understanding the two entities of dyspraxia and DCD proves problematic, both when defining the concepts of praxis/motor coordination and when providing a theoretical analysis of the deficits they cover. More specifically, we aim at exploring the arguments supporting the hypothesis of a specific deficit in praxis development. We discuss the respective contributions of different impairment levels highlighted by studies of developmental gestural impairment (e.g. knowledge, executive functions, perceptive abilities…). Such a deconstruction of the concept of a specific deficit in praxis development argues in favor of an analysis that does not confuse gestural problems with other deficits made apparent through gesture.