Selective output-discriminative signals in the motor cortex of waking monkeys.
Selective output-discriminative signals in the motor cortex of waking monkeys.
复制标题
清醒猴子运动皮层中的选择性输出判别信号。
DOI：
10.1093/cercor/2.4.277
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Romo,R
中科院分区：
文献类型：
--
作者：
Mountcastle,VB;Atluri,PP;Romo,R
猴子和人类具有相似的能力，能够区分传递到其手部无毛皮肤的机械正弦信号的频率。在猴子身上进行的精神心理学-电生理学联合实验证明，这种能力取决于在受刺激的手对面的（感觉）半球的3b和1区的神经元中，由所辨别的刺激诱发的周期性夹带活动的周期长度的差异。现在已经在类似训练和辨别的猴子身上进行了相同的实验，在与手臂相对的半球的运动皮层（4区）中，选择性地投射到两个目标中的一个，以指示辨别力（研究了5个半球，1137个神经元）。我们观察到一个选择性的信号，即将到来的正确的歧视，在约25%的区域4活跃的任务中的神经元。神经元放电选择性地发生于频率低于或高于基础刺激的刺激，并且通常在比较刺激开始后200 - 300毫秒内开始。这些神经元放电是非周期性的，没有刺激频率的迹象。在进行辨别的过程中的EMG记录显示，在刺激呈现期间，记录侧对面的手臂的肌肉是沉默的。在动物犯错误的试验期间的记录最常见地显示，辨别操作的输出本身就是错误的，接着是一个适当的手臂投射到错误的目标。我们解释选择性反应在凸轮刺激是一个后歧视信号投射从感觉半球经胼胝体到控制反应手臂的半球的运动区。我们没有得到任何证据表明辨别操作局限于任何特定区域，我们推测它发生在连接一个半球的感觉皮层和另一个半球的运动皮层的分布式系统内的动态活动中。在试验开始时，运动皮层的三分之一的神经元对同侧手的皮肤的压痕作出反应。这些反应从那些与感官刺激密切相关的反应到那些与对侧手即将到来的运动相关的反应。当向警觉但无所事事的猴子提供类似序列的机械刺激时，不会发生这些发作反应。
Monkeys and humans have similar capacities to discnminate between the frequencies of mechanical sinusoids delivered to the glabrous skin of their hands. Combined psychophysical-electrophysiological experiments in monkeys discriminating in the range of flutter provided evidence that this capacity depends upon differences in the cycle lengths in the sets of periodically entrained activity, evoked by the stimuli discriminated, in neurons of areas 3b and 1 of the (sensory) hemisphere opposite the stimulated hand.Identical experiments have now been made, in similarly trained and discriminating monkeys, in the motor cortex (area 4) of the hemisphere opposite the arm projecting selectively to one of two targets, to indicate discrimination (five hemispheres, 1137 neurons studied). We observed a selective signal of the upcoming correct discrimination in about 25% of the neurons of area 4 active in the task. The neuronal discharge occurs selectively for stimuli either lower or higher in frequency than that of the base stimulus, and commonly begins within 200–300 msec after onset of the comparison stimulus. These neuronal discharges are aperiodic, with no sign of the stimulus frequencies. EMG recording during performance of the discrimination showed that the muscles of the arm opposite the side of recording were silent during the period of stimulus presentations.Recordings during trials in which the animal made errors showed most commonly that the output of the discrimination operation was itself in error, followed by an appropriate arm projection to the wrong target.We interpret the selective response during the cam parison stimulus to be a postdiscrimination signal projected transcallosally from the sensory hemisphere to the motor area of the hemisphere controlling the responding arm. We obtained no evidence that the discrimination operation is localized to any particular area, and we surmise it to occur in the dynamic activity within the distributed system linking the sensory cortex of one hemisphere and the motor cortex of the other.One-third of the neurons of the motor cortex responded to indentation of the skin of the ipsilateral hand, at trial onset. These responses varied from those closely linked to that sensory stimulus to those linked to the upcoming movement of the contralateral hand. These onset responses did not occur when similar sequences of mechanical stimuli were delivered to alert but idling monkeys.