Preshaping and continuous evolution of motor cortical representations during movement preparation
Preshaping and continuous evolution of motor cortical representations during movement preparation
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DOI：
10.1046/j.1460-9568.2003.02906.x
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发表时间：
2003-10-01
影响因子：
3.4
通讯作者：
Riehle, A
中科院分区：
文献类型：
--
作者：
Bastian, A;Schöner, G;Riehle, A
当一个目标导向的运动被准备时，运动皮层神经元选择性地改变它们的活动，这与运动方向的先验信息有关。然而，关于这个参数的部分信息的神经元表征，我们所知甚少。我们通过训练猴子进行多向中心指向任务来研究这个问题。预备信号提供关于一个、两个或三个可能相邻目标的先验信息，从而操纵对运动方向的确定程度。在1秒的延迟后，响应信号指定一个预先的目标，以指示要执行的实际移动。基于在反应时间间隔内确定的单个运动皮质神经元的定向调谐曲线，我们构建了群体激活（dpa）的分布，然后我们可以在准备期间估计这些分布。我们发现这些分布是由先前的信息预先塑造的，激活的峰值集中在先前的运动方向的范围内。当响应信号接近时，这些峰值变得尖锐，并在该信号之后向指定的运动方向移动。较宽的dpa表示较宽的预运动方向范围。猴子反应时间短的实验比反应时间长的实验的分布更窄。因此，我们的研究为(i)通过关于该参数的部分信息对运动方向的神经元群体表示进行分级预成型，以及（ii）在运动开始的准备期间，预成型的群体表示的持续进化提供了证据。
While a goal-directed movement is prepared, motor cortical neurons selectively change their activity in relation to prior information about movement direction. Only little is known, however, about the neuronal representation of partial information about this parameter. We investigated this question by training monkeys in a multidirectional centre-out pointing task. A preparatory signal provided prior information about one, two or three possible adjacent targets, thus manipulating the level of certainty about movement direction. After a 1-s delay, the response signal specified one of the precued targets to indicate the actual movement to be performed. Based on the directional tuning curves of individual motor cortical neurons determined during the reaction time interval, we constructed distributions of the population activation (DPAs), which we were then able to estimate as well during the preparatory period. We found that these distributions were preshaped by prior information, with peaks of activation centred over the range of precued movement directions. These peaks sharpened as the response signal approached, and shifted to the specified movement direction subsequent to that signal. Wider ranges of precued movement directions were represented by broader DPAs. Trials in which monkeys produced short reaction times were characterized by narrower distributions than trials with long reaction times. Our study thus provides evidence for (i) a graded preshaping of the neuronal population representation of movement direction by partial information about this parameter, and (ii) the continuous evolution of the preshaped population representation during the preparatory period towards movement initiation.