Orientation of the opposition axis in mentally simulated grasping

Five normal subjects were tested in a simulated grasping task. A cylindrical container filled with water was placed on the center of a horizontal monitor screen. Subjects used a precision grip formed by the thumb and index finger of their right hand. After a preliminary run during which the container was present, it was replaced by an image of the upper surface of the cylinder appearing on the horizontal computer screen on which the real cylinder was placed during the preliminary run. In each trial the image was marked with two contact points which defined an opposition axis in various orientations with respect to the frontal plane. The subjects’ task consisted, once shown a stimulus, of judging as quickly as possible whether the previously experienced action of grasping the container full of water and pouring the water out would be easy, difficult or impossible with the fingers placed according to the opposition axis indicated on the circle. Response times were found to be longer for the grasps judged to be more difficult due to the orientation and position of the opposition axis. In a control experiment, three subjects actually performed the grasps with different orientations and positions of the opposition axis. The effects of these parameters on response time followed the same trends as during simulated movements. This result shows that simulated hand movements take into account the same biomechanical limitations as actually performed movements

A dissociation between real and simulated movements in Parkinson's disease

Subcortical lesions have been simultaneously implicated in both real and simulated movement deficits. However, the analysis of the simulated opposition axis in precision grasping reveals that, in individuals with idiopathic bilateral Parkinson's disease motor imagery is impaired and that execution of overt movements is spared. This constitutes the first lesion observation congruent with the anatomical and functional dichotomy between real and simulated movements seen in experimental studies. These results underline the modality-specific nature of motor imagery and show that subcortical damage differentially impacts on motor activity

Mental imaging of motor activity in humans

Motor imagery corresponds to a subliminal activation of the motor system, a system that appears to be involved not only in producing movements, but also in imagining actions, recognising tools and learning by observation, as well as in understanding the behaviour of other people. Recent advances in the field include the use of techniques for mapping brain activity and probing cortical excitability, as well as observation of brain lesioned patients during imaging tasks; these advances provide new insights into the covert aspects of motor activity

Origins of neuropsychology: influence of associationism on XIX century neurologists

In 1796 local residents were shocked, as they saw F J Gall measuring the attributes of the spirit while walking through the streets of Vienna. This surprising story anticipated the battle to be faught later between holists and localizationists, which together with the associationists opposed the prevalling view of Cartesian dualism. The adaptation of the Theory of Association of Ideas to current views in the field of neurology, resulted in a new discipline that considered the aphasia as the result of dissociation or isolation of neural centers controlling language. This theoretical contribution probably was the first attempt to make compatible neurology and psychology, an approach that today offers a new basis for the discussion of issues that belong to the interphase between both disciplines.\ud \ud En 1796 la sociedad europea escandalizada vio por las calles de Viena a F. J. Gall medir los atributos del espíritu. Fue el antecedente que llevó a enfrentar a holistas con localizacionistas. Conceptos que, junto al asociacionismo, se opusieron al dualismo cartesiano imperante. La adaptación a la neurología de la teoría de asociación de ideas generó una nueva disciplina, que consideró a la afasia como la disociación o el aislamiento de los centros neurales que contituirían al lenguaje. Esta renovación conceptual fue el primer intento en compatibilizar la neurología con la psicología, constituyéndose en una base de discusión que hoy nos permite estudiar los puntos de pasaje entre ambas, sin que los protagonistas pierdan su identidad

DEVELOPPEMENT 2010-2015 DE LA RECHERCHE\ud Orientations & Priorités d’action. Institut de Réadaptation Gingras-Lindsay de Montréal. Université de Montréal.\ud 17 juin 2010

Une consultation élargie au sein de l’organisation a permis de mettre en lumière des éléments forts pouvant contribuer au développement de la recherche à l’IRGLM au cours des cinq prochaines années. La consultation se voulait un exercice de démocratisation de la recherche à l’IRGLM à travers lequel les représentants des personnes y oeuvrant s’appropriaient les bases de la nouvelle culture de recherche de l’organisation. Une culture où, sans contredit, l’intégration de la recherche aux autres secteurs d’activités de l’IRGLM deviendra tangible au bénéfice de tous.\ud Les résultats de la consultation démontrent que le développement de la recherche passera immanquablement par davantage de projets dans les domaines prioritaires pour l’organisation dont l’évaluation des technologies, l’appréciation des pratiques cliniques, non cliniques et de gestion actuelles, l’examen et la conception de pratiques novatrices, ainsi que l’évaluation des services et des programmes. Pour ce faire, le développement de la recherche exigera de recruter de nouveaux chercheurs aux expertises complémentaires à celles des chercheurs du site IRGLM du CRIR et de créer des partenariats de recherche, tant à l’externe qu’à l’interne, avec un accent particulier sur les partenariats recherche – clinique. Le rehaussement des connaissances pour le personnel, la formation de la relève en recherche, les activités de partage des connaissances et le soutien à l’application des connaissances scientifiques seront autant de moyens pour renforcer le rapprochement de la recherche vers les autres secteurs d’activités de l’organisation, en vue d’optimiser la contribution de la recherche à la réalisation de la mission de l’IRGLM. Finalement, pour soutenir le développement visé, l’IRGLM devra se doter d’une structure souple de fonctionnement pour la recherche afin de s’adapter aux activités scientifiques croissantes.\ud Tous les secteurs d’activités de l’IRGLM s’intéressent à la recherche et en retour, tous les chercheurs du site IRGLM du CRIR sont intéressés par ces secteurs d’activités et les clientèles qui y sont desservies. De plus, il importe de souligner que tous les groupes consultés incluant les chercheurs reconnaissent l’importance du changement organisationnel en cours et les occasions de projets futurs qui en découleront.\ud Ce document présente les orientations et les priorités d’action retenues à la suite de l’analyse des informations recueillies à l’automne-hiver 2009-2010. Les trois (3) grandes orientations spécifiques à la recherche, qui se dégagent de la consultation, sont formulées comme suit.\ud « Développer une programmation de recherche distinctive au sein du CRIR, en reflet des besoins\ud de la clientèle de l’IRGLM et de sa réalité organisationnelle »\ud « Maximiser l’apport de la recherche et des connaissances produites dans les processus\ud décisionnels et l’innovation »\ud « Cultiver un environnement stimulant et prolifique pour la formation académique d’une relève\ud scientifique

Etude de l'onde P300 somesthésique chez deux malades atteints d'asymbolie à la douleur

*L'association d'une lésion préfrontale médiale et cingulaire antérieure bilatérales, avec une lésion insulaire pourrait être le facteur déterminant du syndrome d 'asymbolie à la douleur chez nos malades.\ud \ud *L'absence de P300 somesthésique sur le scalp (malgré un comptage correct),pourrait être déterminée par des lésions des générateurs et des groupes" antécédents" et "gâchettes".\ud \ud *Cette absence tend à démontrer que I'asymbolie à la douleur représente vraisemblablement une indifférence affective, non seulement à la douleur, mais aussi à la stimulation non douloureuse.\ud \ud *ll est tout à fait souhaitable d' étudier de nouveaux cas pour vérifier ces données.\ud \ud *Les futures recherches électrophysiologiques sur l'asymbolie à la douleur devront tenir compte des potentiels évoqués cognitifs dans les trois modalités (auditive,visuelle et somesthésique ) afin d'observer si I'asymbolie à la douleur est une atteinte plurisensorielle ou non

Simulated precision grasping in Parkinson’s Disease.

Subcortical lesions have been simultaneously implicated in both real and simulated movement deficits, suggesting that as with frontal le- sions, self action representation and programmation are the same process. We have analyzed the simulated precision grasping in subjects with idiopathic bilateral PD compared to a healthy control group. Re- sults showed that individuals with PD are impaired in the mental rep- resentation of a grasp orientation but are still capable of normally ex- ecuting this movement. These observations reveal that programmation and execution of movements is spared and that motor representation is selectively impaired. Thus, programmation of real acts and representa- tion of motor action are distinct processes

The role of sensation for hand function in children with cerebral palsy

This chapter reviews the importance of sensations such as vision, as well as cutaneous sensibility and proprioception for the refined motor control of the hand. Intact sensory receptors provide input needed for modulation and adjustment of movements to ensure that they are accurate and smooth. Cerebral palsy is a non-progressive disorder of movement and posture, often accompanied by disturbances of sensation. For rehabilitation specialists evaluating children with CP in the clinical setting, it is essential that the potential influence of sensory impairments be considered, as it may impact on sensory-motor integration needed for refined hand movements to execute everyday tasks and activities. Therapeutic interventions may focus on maximizing tactile sensibility using sensory retraining and stimulation approaches, with the expectation that sensory input will improve and prehension patterns will become more precise. Conversely, capitalizing on more intact sensory modalities and use of adaptive strategies may be employed to enhance learning of functional hand skills, in spite of sensory-motor deficits. Evidence to support the effectiveness of either remediation or compensatory approaches is lacking, and needs to be addressed in future studies, so as to promote hand function needed to independently execute everyday self-care, school and leisure activities in children and youth with CP

A Simple Technique to Study Embodied Language Processes: The Grip-Force Sensor

Research in cognitive neuroscience has shown that brain structures serving perceptual, emotional, and motor processes are also recruited during the understanding of language when it refers to emotion, perception, and action. However, the exact linguistic and extra-linguistic conditions under which such language-induced activity in modality specific cortex is triggered are not yet well understood. The purpose of this study is to introduce a simple experimental technique that allows for the online measure of language-induced activity in motor structures of the brain. This technique consists in the use of a grip force sensor that captures subtle grip force variations while subjects listen to words and sentences. Since grip force reflects activity in motor brain structures, the continuous monitoring of force fluctuations provides a fine-grained estimation of motor activity across time. In other terms, this method allows for both the localization of the source of language-induced activity to motor brain structures and the high temporal resolution of the recorded data. To facilitate comparison of data to be collected with this tool, we present two experiments that describe in detail the technical set up, the nature of the recorded data, and analyses (including justification about data filtering and artifact rejection) that we applied. We also discuss how the tool could be used in other domains of behavioral research

An instrumented cylinder measuring pinch force and orientation

Background: The function of a cylinder allowing simultaneous measurements of the opposition axis of the index finger and thumb of the hand and the magnitude of pinch force is described.\ud Methods: The apparatus is made of two half-cylinders that are bonded together through a 6-axis force/torque sensor and allows the measurement of 3D orthogonal forces and moments of force. The amplitude of the pinch force exerted on the cylinder by the fingers is defined as the resultant of the forces in the different axes. A software program was developed to measure the barycentre of the forces on the instrumented cylinder, allowing calculation of the angle of the opposition axis between the fingers and the location of the resulting pinch force on the cylinder, assuming that the pinch or grip forces are co-linear through the center of the cylinder.\ud In order to assess the validity and reliability of the measurements, the cylinder was mounted on a milling table and seven calibrated weights (from 100 to 500 g) were successively applied perpendicularly to a 9*9 matrix of sites separated by 1 cm. With the exception of the extreme lateral parts of the cylinder, the dispersion of the calculated vertical position of the resulting force was always within 1 mm of the application point, suggesting a high reliability of these measurements. In addition, the errors in the angles of the applied force were calculated and found to be less than 2 degree with no clear patterns of variation across the different locations of the cylinder.\ud Results: The usefulness of the cylinder is demonstrated by evaluating the pinch force and the opposition axis in six healthy subjects lifting the cylinder from the table using three different orientations of their right hand. The magnitude of the grip force was not significantly different across orientations (45, 22 and -22 degrees relative to the midline of the subject) suggesting that force grip is controlled.\ud Conclusion: From these results, it has been concluded that the cylinder is a valid, reliable and precise instrument that may prove useful for evaluating opposition axis and grip force in healthy and pathological populations