Cisek Paul, Kalaska John F
Département de Physiologie, Université de Montréal, Montréal (Québec) H3C 3J7, Canada.
Neuron. 2005 Mar 3;45(5):801-14. doi: 10.1016/j.neuron.2005.01.027.
We show that while a primate chooses between two reaching actions, its motor system first represents both options and later reflects selection between them. When two potential targets appeared, many (43%) task-related, directionally tuned cells in dorsal premotor cortex (PMd) discharged if one of the targets was near their preferred direction. At the population level, this generated two simultaneous sustained directional signals corresponding to the current reach options. After a subsequent nonspatial cue identified the correct target, the corresponding directional signal increased, and the signal for the rejected target was suppressed. The PMd population reliably predicted the monkey's response choice, including errors. This supports a planning model in which multiple reach options are initially specified and then gradually eliminated in a competition for overt execution, as more information accumulates.
我们发现，当灵长类动物在两种伸手动作之间进行选择时，其运动系统首先会呈现出两种选择，随后反映出对它们的选择。当出现两个潜在目标时，如果其中一个目标靠近其偏好方向，背侧运动前皮层（PMd）中许多（43%）与任务相关的、方向调谐细胞就会放电。在群体水平上，这产生了两个同时存在的持续方向信号，对应于当前的伸手选择。在随后的非空间线索确定了正确目标后，相应的方向信号增强，而被拒绝目标的信号则被抑制。PMd群体能够可靠地预测猴子的反应选择，包括错误选择。这支持了一种规划模型，即随着更多信息的积累，多个伸手选择最初被指定，然后在公开执行的竞争中逐渐被淘汰。
