抄録
In the Japanese monkey, our recent PET study has shown that the primary motor cortex (M1) and the supplementary motor area were co-activated during bipedal (Bp) locomotion on the treadmill. To elucidate M1 mechanisms related to the control of Bp locomotion, we injected muscimol unilaterally into the digit/ankle, knee, hip and trunk representations within M1. Local injections of muscimol (5μg/μl, 1μl/site) were used to partially inactivate the M1 region identified with MRI and intracortical microstimulation. We found that unilateral M1 injections impaired movements of hindlimb joints, resulting in claudication on the side contralateral to the injection. The most pronounced effect was the foot-drop-like impairment following injection into the digit/ankle region. These impairments were due to a flaccid paresis predominantly observed in the counterpart of inactivated cortical region. Following injections into the trunk region, the monkey slightly dragged contralateral hindlimb with tilting the trunk forward. Despite the asymmetrical gait due to claudication, the cyclic movement of each hindlimb joint was replicable to some extent, however, in the manner different from that observed before muscimol injections. Our results suggest that M1 contributes to the elaboration and step-by-step control of ongoing Bp locomotion with selective adjustments of moment-to-moment movements of the trunk and hindlimbs. [Jpn J Physiol 54 Suppl:S184 (2004)]
