Possible involvement of primary motor cortex in mentally simulated movement

TLDR

The role of the primary motor cortex (M1) during mental simulation of movement is open to debate. fMRI signals were recorded in normal right‑handed subjects while they performed or imagined a finger‑to‑thumb opposition task with either hand. Motor imagery produced contralateral M1 activation (≈30 % of execution activity) in most subjects, bilaterally engaged premotor cortex and rostral posterior SMA, and showed no hand‑specific differences, supporting that imagery engages nearly all motor control stages.

Abstract

The role of the primary motor cortex (M1) during mental simulation of movement is open to debate. In the present study, functional magnetic resonance imaging (fMRI) signals were measured in normal right-handed subjects during actual and mental execution of a finger-to-thumb opposition task with either the right or the left hand. There were no significant differences between the two hands with either execution or simulation. A significant involvement of contralateral M1 (30% of the activity found during execution) was detected in four of six subjects. Premotor cortex (PM) and the rostral part of the posterior SMA were activated bilaterally during motor imagery. These findings support the hypothesis that motor imagery involves virtually all stages of motor control.