Comparison between the motor inhibitory mechanisms during a simple and choice reaction time tasks

Details

Supervisors

Duque, Julie ; Quoilin, Caroline

Faculty

Faculté des sciences de la motricité

Degree label

Master [60] en kinésithérapie et réadaptation

Abstract

Several models postulate the operation of two motor inhibitory mechanisms during action selection. One called “competition resolution (CR)” may exert global inhibitory influences over the motor output system to assist action selection. The other related to “impulse control (IC)” may exert specific inhibitory influences over selected response to prevent its premature release. To date, these mechanisms have been mostly investigated using delay-reaction time tasks in which the imperative signal is preceded by a delay period requiring subjects to withhold prepared responses. Hence, it is unclear whether the inhibition observed in non-responding effectors during the RT period reflects remnants of the delay period or whether inhibitory processes as the CR are specifically recruited. To address this issue, motor evoked potentials (MEPs) were elicited by transcranial magnetic stimulation (TMS) in both hands during two tasks that either required making a choice between two index finger responses or responding always with the same index finger depending on an imperative signal presented in the absence of any delay period. Overall, the results suggest that in the absence of delay period, there is a strong attenuation of inhibitory markers during the RT period. However, we have some evidence to believe that inhibition occurred during the RT period of the CRT task but was masked by co-occurring facilitatory changes.