Task-related coding of stimulus and response in cat motor cortex.
Task-related coding of stimulus and response in cat motor cortex.
复制标题
猫运动皮层中与任务相关的刺激和反应编码。
DOI：
10.1007/bf00237829
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发表时间：
1985
影响因子：
2
通讯作者：
Ghez,C
中科院分区：
文献类型：
--
作者：
Martin,JH;Ghez,C
在以前的一项研究中的猫，我们已经报告说，运动皮层神经元放电开始前的一个有针对性的前臂反应（铅细胞）更好地定时到运动的显示（刺激）比响应。本研究的目的是区分这种早期活动在运动皮层的放电模式中的刺激和反应特征的编码。单个神经元被记录在三只猫的运动皮层的手臂区域执行相同的一对反应（前臂屈曲和伸展），但显示在两个方向中的任一个通过改变显示极性的运动。在所有条件下，铅细胞活性的调制取决于学习运动反应的发生和刺激的时间。大多数铅细胞（88%，n = 50）属于两个不同的类别之一。在一类神经元中，力方向（56%，n = 32），活动取决于前肢反应的单一方向（屈曲或伸展），因此与显示刺激的方向无关。只有前肢屈肌和伸肌的模式与这类反应相关神经元的活动相匹配。在这些神经元中，根据引起适当反应的刺激方向，将调制的开始定时到两个刺激中的一个或另一个。因此，这些神经元的显示相关输入根据所需的响应而变化。在第二类神经元中，刺激方向（32%，n = 18），调制与特定的刺激方向，而不是响应方向。在不同的任务条件下，这些神经元的活动模式类似于肩和颈部肌肉的EMG信号的模式。近端和轴向肌肉的收缩对应于刺激引起的第二种反应，即头部朝向移动显示器旋转的尝试，并且在开始时间和方向上都独立于条件化前肢反应。为了测试刺激方向神经元参与头部旋转控制的可能性，我们训练了两只动物，使它们在不做出前肢反应的情况下，也能在移动显示器的方向上产生颈部扭矩的等距变化。在颈部任务的执行过程中，刺激方向神经元的活动也受到类似的调制。相比之下，在颈部任务期间检查的力方向神经元在颈部反应后未被调制或放电。这些数据表明，力方向神经元参与反应的启动，它们的活动是由特定于任务的刺激触发的。运动皮层的输入重组可能是与行为定势相关的门控机制的结果。这样的神经门可以提供一系列行为相关刺激的任何成员到躯体组织运动区的受限部分的有效转移。
In a previous study in the cat, we have reported that motor cortex neurons discharging before the initiation of an aimed forearm response (lead cells) are better timed to movement of a display (stimulus) than to the response. The present study was done to distinguish the coding of stimulus and response features in the discharge patterns of such early activity in motor cortex. Single neurons were recorded in the arm area of motor cortex in three cats performing the same pair of responses (forearm flexion and extension) but to display movements in either of the two directions by changing display polarity. The modulation of lead cell activity was contingent on the occurrence of the learned motor response and timed to the stimulus in all conditions. The majority of lead cells (88%,n = 50) fell into one of two distinct classes. In one class of neurons,force-direction(56%,n = 32), activity was contingent on a single direction of forelimb response (flexion or extension) and was thus independent of the direction of the display stimulus. The only muscles whose patterns matched the activity of this class of response-related neurons were forelimb flexors and extensors. In these neurons, the onset of modulation was timed to one or the other of the two stimuli according to the stimulus direction which elicited the appropriate response. Thus, the display-related input to these neurons varied according to the response required. In the second class of neurons,stimulus-direction(32%,n = 18), modulation was associated with a specific stimulus direction rather than the response direction. The pattern of activity of these neurons was similar to the pattern of EMG signals of shoulder and neck muscles during the different task conditions. The contraction of proximal and axial muscles corresponded to a second response elicited by the stimulus, namely attempts at head rotation towards the moving display and was independent of the conditioned forelimb response in both time of onset and direction. To test the possibility that stimulus-direction neurons participated in the control of head rotation we trained two of the animals to also produce isometric changes in neck torque in the direction of the moving display without making the forelimb response. The activity of stimulus-direction neurons was similarly modulated during performance of the neck task. By contrast, force-direction neurons examined during the neck task were either unmodulated or discharged after the neck response. These data suggest that force-direction neurons participate in response initiation and that their activity is triggered by stimuli specific for the task. The reorganization of the inputs to motor cortex is likely to result from gating mechanisms associated with behavioral set. Such neural gates could provide for the efficient transfer of any member of an array of behaviorally relevant stimuli to restricted sectors of the somatotopically organized motor areas.