Cortical and basal-ganglia mechanisms related to the control of bipedal locomotion in a freely-moving monkey

我们已经证明，日本猴（M.fuscata）可以操作性条件反射四足或两足行走的表面上移动跑步机带。为了进一步了解灵长类动物运动控制的皮层机制，我们首先灭活了猴的初级运动皮层（M1）、辅助运动区（SMA）和背侧运动前区（PMd）。在失活研究中，我们选择性地将GABA_A激动剂蝇蕈醇注射到M1、SMA和PMd的躯干和/或后肢区，观察其神经元活动。我们发现，单侧注射到M1产生松弛性轻瘫，而限制部分后肢对侧注射侧，导致跛行。最明显的效果是注射到手指和脚踝区域后出现足下垂样损伤。双侧SMA注射可使患者的姿势肌张力普遍降低， 关于我们 躯干和后肢，产生蹒跚的步态模式。双侧注射到PMD损害的自发运动的启动响应的介绍食物奖励。在单单位记录研究中，使用定制的微操作器将钨微电极插入M1和PMd的后肢区域。我们发现，所有的神经元记录在M1调制他们的放电相位锁定的步骤周期或增加他们的放电频率在运动过程中的紧张性。表现出相位调制的神经元每步达到一次或两次峰值。大多数人增加了他们的放电频率随着跑步机速度的增加。在PMd中，许多记录到的神经元在运动开始前后的放电频率呈紧张性增加，这些结果表明，猴子的皮层运动区以不同的方式参与运动的加工和控制，并表明M1参与躯干和后肢运动的逐步调整，SMA参与伴随姿势的瞬间调整，PMd参与运动的启动。少

We have shown that the Japanese monkey (M.fuscata) could be operant-conditioned to walk quadrupedally or bipedally on the surface of a moving treadmill belt. To further our understanding of cortical mechanisms related to the control of primate locomotion, we first inactivated primary motor cortex (M1), supplementary motor area (SMA) and dorsal premotor area (PMd) of the monkey. We then recorded neuronal activity in M1 and PMd during the execution of locomotor movements on the treadmill.In the inactivation study, we injected GABA_A agonist, muscimol, selectively into trunk and/or hindlimb regions of M1, SMA and PMd. We found that unilateral injections into M1 produced flaccid paresis in rather restricted part of the hindlimb contralateral to the injection side, resulting in claudication. The most pronounced effect was the foot-drop-like impairment following injections into the digit and ankle regions. Bilateral injections into SMA produced a general reduction of postural muscle tone in … More the trunk and hindlimbs, yielding a tottering gait pattern. Bilateral injections into PMd impaired the initiation of locomotor movements in response to the presentation of food rewards. In the single-unit recording study, tungsten microelectrodes were inserted into hindlimb region of M1 and PMd using a custom-made micro-manipulator. We found that all neurons recorded in M1 modulated their discharge phasically time-locked to the step cycle or increased their discharge frequency tonically during locomotion. The neuron exhibiting phasic modulation peaked once or twice per step. Most of them increased their discharge frequency as the treadmill speed increased. In PMd, many recorded neurons increased their discharge frequency tonically around the initiation of locomotion.These results demonstrate that cortical motor areas of the monkey contribute in a different manner to the elaboration and control of locomotion, and suggest that M1 contributes to the step-by-step adjustments of the trunk and hindlimb movements, SMA contributes to the moment-to-moment adjustments of accompanying posture, and PMd contributes to the initiation of locomotion. Less