Investigating the Role of Primary Motor Cortex in Manual Inhibition of Return Effects: A Transcranial Magnetic Stimulation Study

Inhibition of return (IOR) is a behavioural phenomenon characterised by longer response times (RTs) to stimuli presented at previously cued versus uncued locations. The neural mechanisms underlying IOR effects are not fully understood. Previous neurophysiological studies have identified a role of frontoparietal areas including posterior parietal cortex (PPC) in the generation of IOR, but the contribution of primary motor cortex (M1) has not been directly tested. The present study investigated the effects of single-pulse transcranial magnetic stimulation (TMS) over M1 on manual IOR in a key-press task where peripheral (left or right) targets followed a cue at the same or opposite location at different SOAs (100/300/600/1000ms). In Experiment 1, TMS was applied over right M1 on a randomised 50% of trials. In Experiment 2, active or sham stimulation was provided in separate blocks.IOR was observed in RTs at longer SOAs in the absence of TMS (non-TMS trials in Experiment 1 and Sham trials in Experiment 2). In both experiments, TMS was found to alter IOR effects bilaterally. Additionally, early facilitatory cueing effects were observed in TMS trials of Experiment 1. The magnitude of motor-evoked potentials was not altered by the cue-target relationship in either experiment.These findings do not support a key role of M1 in the mechanisms of IOR. Instead, activity in M1 may influence the expression of IOR via reciprocal connections to regions involved in salience and motor response selection such as the PPC.

Note:
Funding Information: This research was supported by the Natural Sciences and Engineering Research Council of Canada.

Conflict of Interests: None.

Ethical Approval: All procedures were approved by the University of Toronto Ethics Review Office and participants provided written informed consent.

Keywords: Inhibition of return, inhibitory control, transcranial magnetic stimulation, primary motor cortex, M1

Suggested Citation: Suggested Citation

Bek, Judith and Constable, Merryn D. and Hilchey, Matthew and Welsh, Timothy, Investigating the Role of Primary Motor Cortex in Manual Inhibition of Return Effects: A Transcranial Magnetic Stimulation Study. Available at SSRN: https://ssrn.com/abstract=4162516 or http://dx.doi.org/10.2139/ssrn.4162516