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）可以在操作条件下在移动的跑步机带表面上四足或两足行走。为了进一步了解与灵长类动物运动控制相关的皮质机制，我们首先灭活了猴子的初级运动皮质（M1）、辅助运动区（SMA）和背侧运动前区（PMd）。然后，我们记录了在跑步机上进行运动运动时M1和PMd的神经元活动。在失活研究中，我们选择性地将GABA_A激动剂muscimol注射到M1、SMA和PMd的躯干和/或后肢区域。我们发现单侧注射M1在注射侧后肢相当受限的部分产生弛缓性轻瘫，导致跛行。最明显的效果是在向手指和脚踝区域注射后产生的足滴样损伤。双侧注射SMA可使躯干和后肢的体位肌张力普遍降低，导致步履蹒跚。双侧注射PMd损害了对食物奖励的反应的运动运动的启动。在单单元记录研究中，使用定制的微机械臂将钨微电极插入M1和PMd的后肢区域。我们发现，在运动过程中，所有记录在M1区的神经元的放电都是周期性地定时锁定到阶跃周期，或者是紧张性地增加放电频率。表现出相位调制的神经元每步达到一次或两次峰值。随着跑步机速度的增加，大多数小鼠的放电频率增加。在PMd中，许多记录到的神经元在运动开始前后紧张性地增加放电频率。这些结果表明，猴皮层运动区以不同的方式参与了运动的精细和控制，M1参与了躯干和后肢运动的逐步调整，SMA参与了伴随姿势的瞬间调整，PMd参与了运动的启动。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