Unusual use of objects after unilateral brain damage. The technical reasoning model.

International audienceIt has been suggested that gesture engrams, conceptual knowledge and/or the ability to infer function from structure can support object use. The present paper proposes an alternative view which is based upon the idea that object use requires solely the ability to reason about technical means provided by objects. Technical means are abstract principles which are not linked with any object representation (e.g., cutting involves the opposition between dense and permeable material). The technical reasoning model predicts that the inability to perform technical reasoning should impair performance in any situation requiring the use of objects (in a conventional way or not). Twenty left brain-damaged (LBD) patients, 11 right brain-damaged (RBD) patients and 41 healthy controls were examined on experimental tests assessing the conventional use of objects (e.g., screwing a screw with a screwdriver), conceptual knowledge about object function, pantomime of object use and recognition of object utilization gestures. We also designed the Unusual Use of Objects test, which demands unusual applications of objects to achieve a purpose for which the usually applied object is not provided (e.g., screwing a screw with a knife). The key findings are that only LBD patients have more difficulties on the Unusual Use of Objects Test than controls or RBD patients, and that the severity of their impairment is correlated with that on conventional use of objects. Correlations with tests assessing conceptual knowledge as well as with tests of pantomime of object use and recognition of object utilization gestures were weaker. These results support the technical reasoning model and question the role of conceptual knowledge and gesture engrams in object use. Since the technical reasoning model also predicts two distinct technical disorders, the discussion focuses on the existence of these disorders in regard to individual performance profiles obtained in the Unusual Use of Objects test

Validation de la valeur prédictive du rapport ABETA42/ABETA40 du liquide cérébro-spinal pour le diagnostic de la maladie d'Alzheimer

cérébrospinal de 3 des protéines impliquées dans la maladie d Alzheimer (MA) T-Tau (tau total), P-tau (tau phosphorylé) et Abéta42 (Ab42) sont proposées comme un des nouveaux critères pour ce diagnostic.Nous avons voulu confirmer la place du ratio Ab42/Ab40 en pratique clinique. Nous avons étudié les biomarqueurs Ab42, Ab40 et P-tau chez 165 patients avec une MA (n=77), une autre démence (OD, n=30), un mild cognitive impairment (n=4), MCI ayant évolué en MA (n=15), MCI avec une part vasculaire (n=3), démence à corps de Lewy (n=8), atrophie focale (n=9) et des patients présentant une démence d origine non dégénérative (ND, n=19). Les patients MA étaient significativement différents des patients ND en utilisant la moyenne de P-tau, Ab42 et du ratio Ab42/Ab40, de même pour la comparaison des patients MA et OD. La sensibilité était de 96 %, la spécificité de 63 %, la valeur prédictive positive de 90 %, la valeur prédictive négative de 80 % pour différencier les groupes MA et ND. L'originalité de cette étude repose sur le caractère homogène de l'analyse clinique et biochimique. Ce ratio permet de distinguer le groupes MA du groupe ND. Toutefois il manque de spécificité à l'échelle individuelle. Des pistes sont proposées pour combiner différents biomarqueurs afin d'améliorer cette spécificité.ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Gestural apraxia

International audienceGestural apraxia was first described in 1905 by Hugo Karl Liepmann. While his description is still used, the actual terms are often confusing. The cognitive approach using models proposes thinking of the condition in terms of production and conceptual knowledge. The underlying cognitive processes are still being debated, as are also the optimal ways to assess them. Several neuroimaging studies have revealed the involvement of a left-lateralized frontoparietal network, with preferential activation of the superior parietal lobe, intraparietal sulcus and inferior parietal cortex. The presence of apraxia after a stroke is prevalent, and the incidence is sufficient to propose rehabilitation

The potential of virtual reality-based training to enhance the functional autonomy of Alzheimer's disease patients in cooking activities: A single case study.

International audienceImpairments in performing activities of daily living occur early in the course of Alzheimer's disease (AD). There is a great need to develop non-pharmacological therapeutic interventions likely to reduce dependency in everyday activities in AD patients. This study investigated whether it was possible to increase autonomy in these patients in cooking activities using interventions based on errorless learning, vanishing-cue, and virtual reality techniques. We recruited a 79-year-old woman who met NINCDS-ADRDA criteria for probable AD. She was trained in four cooking tasks for four days per task, one hour per day, in virtual and in real conditions. Outcome measures included subjective data concerning the therapeutic intervention and the experience of virtual reality, repeated assessments of training activities, neuropsychological scores, and self-esteem and quality of life measures. The results indicated that our patient could relearn some cooking activities using virtual reality techniques. Transfer to real life was also observed. Improvement of the task performance remained stable over time. This case report supports the value of a non-immersive virtual kitchen to help people with AD to relearn cooking activities

A contribution to the study of environmental dependency phenomena: The social hypothesis

International audienceEnvironmental dependency phenomena refer to the symptoms initially described by Lhermitte (1983, 1984) under the terms of “utilization behavior” and “imitation behavior”. These clinical signs are linked to essential notions such as free-will and human autonomy, and seem to be specific of the frontal pathology. Surprisingly, few studies have addressed these symptoms and inconsistent definitions are available. To investigate the theoretical and clinical definitions of environmental dependency phenomena, three groups of neurological patients (n = 60) with frontal, subcortical, and posterior brain lesions were compared. Clinically, our findings help to rehabilitate the definitions of Lhermitte (1983, 1984) and challenge the classical interpretation in terms of an executive control deficit. The frontal specificity of the disorders and the lack of relation between executive/behavioral deficits were supported. The right orbitofrontal cortex seems particularly involved in environmental dependency. These results offer some evidences for differentiate two historical concepts of neuropsychology, namely the “frontal” and “dysexecutive” syndromes. A new interpretation of environmental dependency phenomena is provided which could be helpful to orient the neuropsychology of frontal syndrome

: A dissociation between executive control and utilization behavior.

Lhermitte (Brain 1983 ; 106 : 237-55) a proposé le terme de " comportement d'utilisation d'objets " (CUO) pour caractériser un syndrome neurologique particulier : sans injonction de l'examinateur, la présentation visuotactile d'objets suffit à ce que les patients s'en saisissent et les utilisent. Lhermitte envisage ce comportement comme la conséquence de lésions frontales et le considère comme un aspect central du " syndrome de dépendance à l'environnement " (Ann Neurol 1986 ; 19 : 335-43). Par la suite, Shallice et al. (Brain 1989 ; 112 : 1587-98) ont remis en cause la procédure d'investigation développée par Lhermitte (Brain 1983 ; 106 : 237-55), en proposant une autre méthodologie de recherche qui conduit à dissocier deux formes de CUO. Il n'existe pas de comparaison de ces deux procédures chez un même groupe de patients. Nous avons recherché le CUO chez 40 sujets (20 patients frontaux et 20 sujets témoins appariés) à partir des protocoles de Lhermitte (Brain 1983 ; 106 : 237-55) et de Shallice et al. (Brain 1989 ; 112 : 1587-98). Par ailleurs, pour mettre à l'épreuve l'interprétation cognitive du CUO comme l'expression d'un défaut du contrôle exécutif, nous avons étudié les liens entre ce comportement et les performances aux épreuves exécutives. Les résultats montrent que les deux formes de CUO peuvent apparaître indépendamment. De plus, il n'existe pas de corrélation entre le CUO et les scores aux différents tests, suggérant une dissociation entre ce comportement et les capacités de contrôle cognitif

Theory of Mind and social reserve: Alternative hypothesis of progressive Theory of Mind decay during different stages of Alzheimer’s disease

International audienceAlthough Theory of Mind (ToM) is thought to be impaired in Alzheimer’s disease (AD), it remains unclear whether this impairment is linked to the level of task complexity, the heterogeneity of the studied patients, or the implication of executive dysfunctions. To elucidate this point, 42 AD patients, divided into two subgroups [moderate AD (mAD) patients (n = 19) and early AD (eAD) patients (n = 23)], and 23 matched healthy older subjects (HO) were enrolled. All participants were given (1) a false-belief task (cognitive ToM), (2) a revised version of the “Reading the Mind in the Eyes” test (affective ToM), and (3) a composite task designed to assess ToM abilities with minimal cognitive demands. Participants were also given executive tasks assessing inhibition, shifting, and updating processes. We observed a significant impairment of cognitive and composite ToM abilities in eAD patients compared with mAD patients. There was no impairment of affective ToM. Stepwise regression revealed that measures of global efficiency and executive functions (EFs) were the best predictors of progressive decay of ToM scores. These results indicate that cognitive aspects of ToM are more sensitive to AD progression than affective tasks. They also show that ToM abilities are more affected by dementia severity than by task complexity. One explanation of our results is the presence of compensatory mechanisms (social reserve) in AD

Les multiples facettes des pantomimes d'utilisation d'outils

International audiencePantomiming the use of familiar tools is a central test in the assessment of apraxia. Indeed, this task is quite sensitive to detect apraxia in patients with left brain damage, particularly when the lesions fall into the parietal lobe. However, surprisingly, the nature of the underlying cognitive mechanisms remains a matter of debate. It has been proposed that activation of manipulation knowledge was a prerequisite to perform pantomime actions. This type of knowledge informs individuals about how to manipulate tools (e.g., knowing that the use of a hammer is associated with oscillations of the elbow). In recent years, for the technical reasoning hypothesis, it has been argued that the ability to pantomime the use of a tool can be explained without invoking activation of manipulation knowledge. The demonstration by pantomime, like any other situation involving tool use, requires mechanical knowledge to create a representation of the action. Thus, pantomimes are not available in long-term memory and they have to be reconstructed de novo. In this review, we attempt to redefine pantomime of tool use activity according to recent results reported in the literature ; and to question the real function of pantomimes. To anticipate our conclusions, pantomime of tool use is a multi-determined task, which requires communication skills. Pantomime of tool use is also a powerful screening task, but its interest might be relatively limited when times come to infer impaired cognitive mechanisms.La tâche de pantomimes d'utilisation est couramment utili-sée dans la pratique clinique. C'est une tâche sensible pour détecter des troubles praxiques chez des patients porteurs de lésions pariétales gauches. D'un point de vue des mécanismes cognitifs impliqués, il est largement admis que pour produire un pantomime, il est nécessaire d'activer des connaissances sur la manipulation. Cepen-dant, le développement récent de nouvelles modélisations cognitives de l'apraxie ont remis en question l'approche traditionnelle et nous incite à repenser les pantomimes d'utilisation d'outils. Dans le cadre de l'approche basée sur le raisonnement technique, produire un pantomime d'utilisation d'outils ne nécessiterait pas d'activation de connaissances en mémoire à long terme mais plutôt la reconstruction de novo dans un espace donné d'une représentation associée à une utilisation et de maintenir temporairement cette représentation. Cette remise en question nous incite à redéfinir cette activité gestuelle tout en considérant sa fonction qui pourrait être avant tout une fonction de communication

Utilization behavior: Clinical and theoretical approaches

International audienceLhermitte (1983) coined the term "utilization behavior" (UB) to define a neurobehavioral syndrome in which the visuo-tactile presentation of objects compels patients to grasp and use them, despite the fact that they have not been instructed to do so. The author suggested that UB was the consequence of frontal lobe damage. Thereafter, Shallice, Burgess, Schon, and Baxter (1989) questioned Lhermitte's (1983) procedure for eliciting UB, putting forward an alternative research methodology that led to differentiate two forms of UB: "induced" and "incidental." To date, there has been no direct comparison between these two procedures, nor have any other methodologies been used to explore this clinical sign, which is related to fundamental concepts such as free will and human autonomy. We investigated UB in 70 subjects (25 patients with frontal lobe lesions, 10 patients with posterior brain damage and 35 control subjects) using the methodologies of Lhermitte (1983) and Shallice et al. (1989), as well as an original "verbal generation" procedure. Our results show that the verbal generation procedure reveals UB effi ciently and that elicitation of this sign appears to be directly linked to the content of the task. We discuss the interpretation of UB in terms of an executive control defi cit. (JINS , 2010, 16 , 1-10.

Des troubles praxiques aux troubles techniques. Une étude de deux cas

International audienceRésumé Le présent travail propose d'examiner l'hypothèse des engrammes ges-tuels en évaluant deux patientes ambidextres (DP et PM), victimes d'ac-cidents vasculaires cérébraux droits. Ces deux patientes ont présenté un déficit conceptuel associé à des difficultés dans l'exécution des panto-mimes. L'utilisation usuelle et non usuelle d'objets était également per-turbée. Si un déficit de récupération d'engrammes pouvait être évoqué, cette approche n'explique pas la cohérence comportementale des pa-tientes dans les différentes épreuves. Par exemple, la patiente DP tendait à saisir les objets par la partie spécifique (e.g., la lame du tournevis) lors de l'utilisation usuelle des objets. Ce comportement se retrouva lors de l'épreuve d'exécution de pantomimes dans laquelle sa performance sug-gérait clairement une tenue par la partie spécifique. Les conduites rap-portées chez ces deux patientes interrogent la pertinence du concept d'engramme gestuel et étayent la perspective d'une incapacité de raison-ner sur la façon dont les objets peuvent être techniquement utilisés. Mots-clés : Apraxie, utilisation d'objet, pantomime, action, stratégie de compensation