  In this Habilitation Thesis, I synthesize 10 years of work on the role of the
motor system in sensorimotor decision-making. First, a large part of the work
we initially performed (2014-2020) questioned the functional role of the motor
system in the integration of so-called decision variables such as the reward
associated with different actions, the sensory evidence in favor of each action
or the level of urgency in a given context. To this end, although the exact
methodology may have varied, the approach exploited has been to study either
the impact of a perturbation of the primary motor cortex (M1) on the
integration of such decision variables in decision behavior, or the influence
of these variables on changes in M1 activity during the decision. More recently
(2020 - present), we have been investigating the neural origin of some of the
changes in M1 activity observed during decision-making. To answer this
question, a "perturbation-and-measurement" approach is exploited: the activity
of a structure at a distance from M1 is perturbed, and the impact on the
changes in M1 activity during decision-making is measured. The thesis ends up
with a personal reflection on this paradigmatic evolution and discusses some
key questions to be addressed in our field of research.
