Gardiner T W, Nelson R J
Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis 38163.
Exp Brain Res. 1992;92(1):15-26. doi: 10.1007/BF00230379.
Recordings were obtained from 146 neurons in the neostriatum of rhesus monkeys while they performed wrist movements in response to visual and vibratory cues. Of these, 75 putamena nd 29 caudate neurons exhibited changes in firing rate that were temporally related to the onset of the wrist movements and that began prior to movement onset. This premovement activity (PMA) usually was directionally specific, in that the magnitude or direction of change in firing rates was different during flexion trials as compared to trials involving wrist extension. PMA onset usually preceded movement onset by more than 100 ms and in most instances preceded the average onset of task-related changes in electromyographic (EMG) activity in muscles of the wrist and forelimb. For most neurons, the changes in neuronal activity that began prior to movement were maintained during movement execution. However, approximately one-third of the neurons that exhibited PMA changed their firing rate in the opposite direction, relative to their PMA and to their baseline rate of activity, once the movement began. Several other neurons either exhibited PMA only or they altered their discharge rates during movement execution but did not exhibit PMA. These observations suggest that, despite the close temporal relationship between the onset of PMA and the onset of wrist movement, the neuronal mechanisms mediating the PMA may differ from those that occur during movement execution. The PMA onset of neostriatal neurons occurred earlier in visually cued than in vibratory cued trials. These differences were statistically significant only for flexion trials, however, in which movements were made against a load and in the same direction as the palmar vibratory stimulus. For trials involving wrist extension, PMA onsets for visually cued as compared with vibratory cued trials were not statistically different. These findings contrast with data obtained previously from somatosensory cortical neurons during performance of the same behavioral task. On average, PMA in the putamen began earlier, relative to movement onset, than it did in the somatosensory cortex. Moreover, in the somatosensory cortex, PMA onset occurred earlier in vibratory cued than in visually cued trials, irrespective of movement direction (Nelson 1988; Nelson and Douglas 1989). For putamen neurons, but not for caudate or cortical neurons, the onset of PMA also occurred significantly earlier during extension trials than flexion trials, irrespective of the modality of the "go-cue".(ABSTRACT TRUNCATED AT 400 WORDS)
在恒河猴执行腕部运动以响应视觉和振动提示时，从其新纹状体中的146个神经元记录到相关数据。其中，75个壳核神经元和29个尾状核神经元的放电频率发生了变化，这些变化在时间上与腕部运动的开始相关，且在运动开始前就已出现。这种运动前活动（PMA）通常具有方向特异性，即与涉及腕部伸展的试验相比，在屈曲试验中放电频率变化的幅度或方向有所不同。PMA的开始通常比运动开始提前100多毫秒，并且在大多数情况下先于腕部和前肢肌肉中与任务相关的肌电图（EMG）活动的平均开始时间。对于大多数神经元来说，在运动执行期间，在运动开始之前开始的神经元活动变化得以维持。然而，大约三分之一表现出PMA的神经元，一旦运动开始，其放电频率相对于其PMA和基线活动频率向相反方向变化。其他几个神经元要么仅表现出PMA，要么在运动执行期间改变其放电频率，但未表现出PMA。这些观察结果表明，尽管PMA的开始与腕部运动的开始在时间上密切相关，但介导PMA的神经元机制可能与运动执行期间的机制不同。新纹状体神经元的PMA开始在视觉提示试验中比在振动提示试验中更早出现。然而，这些差异仅在屈曲试验中具有统计学意义，在屈曲试验中运动是在有负载的情况下且与掌侧振动刺激方向相同。对于涉及腕部伸展的试验，视觉提示试验与振动提示试验的PMA开始时间在统计学上没有差异。这些发现与之前在执行相同行为任务期间从体感皮层神经元获得的数据形成对比。平均而言，壳核中的PMA相对于运动开始比在体感皮层中开始得更早。此外，在体感皮层中，无论运动方向如何，PMA开始在振动提示试验中比在视觉提示试验中更早出现（Nelson，1988；Nelson和Douglas，1989）。对于壳核神经元，而不是尾状核或皮层神经元，无论“开始提示”的方式如何，在伸展试验中PMA的开始也比屈曲试验中明显更早出现。（摘要截取自400字）
