Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

It has long been recognized that certain types of movements are prepared in advance to allow task requirements to be met. For example, movements that require a fast reaction time (RT), or those performed in the absence of feedback can be completed successfully and accurately if the goal of the action is known in advance. Although humans commonly perform these types of movements with ease, much is unknown regarding how these actions are planned and carried out by the central nervous system. It has been suggested that these movements are governed by “motor programs” that can specify the details of the motor plan to be carried out. Although motor programs have often been thought of as a metaphor to describe preparation for movement, several more literal models have been proposed describing how motor programs may be represented in the brain. Cortical cell assemblies, in the form of strengthened connections between motor cortical neurons, have been proposed as a mechanism for motor program representation. While these contemporary models suggest that motor programs are cortically mediated and stored, here we propose to investigate the hypothesis that motor actions are represented in a distributed network of cortical and subcortical brain structures, and that the relative contribution of each area depends on the functional and/or anatomical requirements of the task to be performed. In order to achieve the goals of this research, the proposed program of research includes four interrelated main aims that build upon one another. These aims will utilize behavioural methods such as RT tasks and kinematic analysis, as well as neurophysiological techniques and analyses, including the use of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) to both probe brain activation and modulate its activity. The first aim is to further characterize the neural activation in the central nervous system and investigate the hypothesis that response preparation and movement initiation are separate processes with overlapping associated neural activation. The second aim is to investigate the hypothesis that cortical, brainstem, and spinal motor areas contribute differential neural activation to action preparation and initiation depending on the nature of the task and task goals. The third aim is to characterize cerebellar activation and its influence on preparatory activity in primary motor cortex in tasks involving complex timing. Finally, the fourth aim is to directly test a brainstem-mediated response initiation neural mechanism by testing whether responses can be involuntarily triggered in particular stroke populations. Overall, the proposed research is expected to have substantial impact in the field of neuroscience, generate numerous high-impact publications and train future research leaders in the control of human movement.