POSSIBLE INVOLVEMENT OF PRIMARY MOTOR CORTEX IN MENTALLY SIMULATED MOVEMENT - A FUNCTIONAL MAGNETIC-RESONANCE-IMAGING STUDY

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 oppos ition task with either the right or the left hand, There were no signi ficant differences between the two hands with either execution or simu lation. A significant involvement of contralateral M1 (30% of the acti vity found during execution) was detected in four of six subjects. Pre motor cortex (PM) and the rostral part of the posterior SMA were activ ated bilaterally during motor imagery. These findings support the hypo thesis that motor imagery involves virtually all stages of motor contr ol.