EVIDENCE FOR FACILITATION OF MOTOR EVOKED-POTENTIALS (MEPS) INDUCED BY MOTOR IMAGERY

This study examined the extent to which motor imagery can facilitate t o specific pools of motoneurons. Motor commands induced by motor image ry were subthreshold for muscle activity and were presumably not assoc iated with any change in background afferent activity. To estimate exc itability changes of flexor carpi radialis (FCR) muscle motoneuron in spinal and cortical level, electric stimuli for recording H-reflex and transcranial magnetic stimulation (TMS) for recording motor evoked po tentials (MEPs) were used. During motor imagery of wrist flexion, rema rkable increases in the amplitude of the MEP of FCR were observed with no change in the H-reflex. Furthermore, facilitation of antagonist (e xtensor carpi radialis; ECR) was also observed. Therefore, it is concl uded that internal motor command can activate precisely cortical excit ability with no change in spinal level without recourse to afferent fe edback.