2 research outputs found
Ătude du Cortex PrĂ©moteur pendant le choix de lâaction lors dâune prise de dĂ©cision entraĂźnant une rĂ©compense.
La prise de dĂ©cision motrice implique que le sujet analyse les diffĂ©rentes stratĂ©gies possibles, en se basant sur lâobservation de son environnement notamment, qui le conduisent Ă une dĂ©cision motrice finale la plus appropriĂ©e.
Pour explorer ce processus, nous avons rĂ©alisĂ© un projet de recherche qui a pour but de deÌterminer comment varie lâactiviteÌ des cellules de trois diffeÌrentes aires motrices du cortex cĂ©rĂ©bral, en fonction de plusieurs indices visuels observĂ©s lors du mĂ©canisme de prise de dĂ©cision complexe. Dans ce contexte, les indices sensoriels utilisĂ©s peuvent soit preÌsenter des indices ambigus ou contradictoires en faveur de diffeÌrents choix dâactions. Ce procĂ©dĂ© nĂ©cessite Ă ce que le cerveau dĂ©termine Ă quel degrĂ© un indice sensoriel est plus en faveur dâun choix que dâun autre, et quel est le meilleur choix dâaction Ă reÌaliser en se basant sur les indices sensoriels reçus durant une pĂ©riode de temps donnĂ©e.
Dans ce projet de thĂšse nous avons enregistreÌ lâactiviteÌ des cellules des aires corticales motrices primaires (M1), du prĂ©-moteur dorsal (PMd), et aussi du prĂ©frontal dorso-latĂ©ral (DLPF), chez un singe, dans plusieurs tĂąches dĂ©cisionnelles dont certaines ont Ă©tĂ© notamment utilisĂ©es au prĂ©alable au sein de notre laboratoire par Coallier et al. (2014,2015). Dans cette thĂšse, nous prĂ©senterons les observations obtenues dans le PMd.
Dans les essais de nos diffĂ©rentes tĂąches, nous avons utilisĂ© des stimuli visuels correspondants Ă des damiers multicolores composeÌs dâun nombre variable de carrĂ©s bleus et jaunes. Ces damiers fournissaient diffĂ©rents niveaux « dâeÌvidences » en faveur des cibles bleues ou jaunes, Ă atteindre en rĂ©alisant un mouvement du bras.
Dans ce projet, nos hypothĂšses sont les suivantes:
1) lâactiviteÌ des cellules du PMd est plus impliquĂ©e dans la sĂ©lection de lâaction que dans les processus perceptuels de la tĂąche, 2) les cellules du PMd pourraient jouer un rĂŽle dans les procĂ©dĂ©s mĂ©tacognitifs tels que la confiance en des choix dâactions.
En conclusion, nos expĂ©riences ont permis de mettre en Ă©vidence des mĂ©canismes neuronaux Ă travers lesquels le cortex prĂ©moteur dorsal (PMd) contribue Ă la planification et Ă lâexeÌcution des mouvements volontaires du bras. Plus preÌciseÌment, nos donneÌes montrent que le PMd est plus impliquĂ© dans les aspects moteurs, que perceptuels de la prise de dĂ©cision sensorimotrice. De plus, le PMd exprime une activitĂ© qui pourrait reflĂ©ter des processus neuronaux par lesquels les singes font un suivi et Ă©valuent leur propre performance dans les tĂąches, afin de prĂ©dire la probabilitĂ© de bonne rĂ©ponse et de rĂ©ussite de leurs dĂ©cisions, et pour attribuer un niveau de confiance en leurs dĂ©cisions.Motor decision-making implies that the subject analyses different possible strategies, based on the observation of his environment in particular, which leads him to select the most appropriate final motor decision.
To explore this process, we conducted a research project to determine how neural activity in the dorsal premotor cortex (PMd) varies according to several visual cues observed during a complex decision-making process. In this context, the sensory instructional cues used may either present ambiguous or even contradictory evidence in favor of different motor choices. This process requires the brain to determine to what degree sensory input is more in favor of one choice than another, and what is the best choice of action to take based on the sensory cues received over a given period of time.
To do so, we recorded the activity of single neurons in the dorsal pre-motor cortex (PMd of a monkey, in several decision-making tasks, some of which were previously used in our laboratory by Coallier et al.(2014, 2015).
We tested neural activity in our different tasks, by using visual stimuli that resembled multicolored checkerboards, composed of a variable number of blue and yellow squares. These checkerboards provided different levels of "evidence" in favor of blue or yellow targets, to be reached by moving the arm.
In this project, our hypothesis are as follows:
1) PMd cell activity is more involved in action selection than in the perceptual processes of the task, 2) PMd cells could play a role in metacognitive processes such as confidence in action choices.
In conclusion, our experiments provided new insights into the neural mechanisms by which the dorsal premotor cortex (PMd) contributes to the planning and execution of voluntary arm movements. In particular, our data show that PMd is more implicated in the motor aspects of sensorimotor decisions and expresses little or no activity related to the perceptual aspects of the decision-making process. Furthermore, PMd neurons express activity that might reflect neuronal processes by which the monkeys monitor and evaluate their performance in the tasks, in order to predict the probability of correct responses and success of their decisions, and to attribute a level of metacognitive confidence in their motor decisions
Macaque dorsal premotor cortex exhibits decision-related activity only when specific stimulusâresponse associations are known
It is not clear to what degree activity in dorsal premotor cortex (PMd) reflects perceptual-deliberation versus action-selection aspects of decision-making. Here, the authors report that monkey PMd neurons do not express correlates of the perceptual decision independently of the action choices