Evolution of intention for voluntary action

为了了解大脑皮层中多个区域在运动行为认知控制中的作用，已经使用非人灵长类动物进行了一系列实验研究。研究兴趣主要集中在动作意图的产生机制和运动行为的认知控制机制。通过检查在执行计划行动期间皮层区域的细胞活动，出现了以下发现。(1)背侧前运动皮层的外侧部分，已知接受视觉和躯体感觉输入，是神经元检索关于目标和身体部位的信息的部位，而随后的活动指定计划的动作。(2)我们发现腹侧前运动皮层的细胞主要反映信息提取的过程。另一方面，背侧前运动皮层的细胞更多地代表了整合空间目标和肢体使用信息的过程，以及随后计划采取“行动”的过程。这种活动是罕见的内侧运动区。(3)扣带运动区的吻侧部分在处理运动选择的奖赏信息中起作用。(4)背外侧前额叶皮层中的细胞在分类水平的行为规划中发挥作用，这是一个比规划单个序列所需的更复杂的认知水平。(5)另一方面，dl-PF中的细胞参与检索和保存有关事件时间序列的信息，以规划随后的运动行为。(6)下顶叶中的细胞被发现反映了受试者本身所采取的行动的数量，从而提供了选择下一个行动的信息。

To understand the role played by multiple areas in the cerebral cortex on cognitive control of motor behavior, a series of experimental studies have been performed using subhuman primates. The research interest was focused on mechanisms for generation of intention for action and for the cognitive control of motor behavior. By examining cellular activity in cortical areas during performance of planned actions, the following findings emerged. (1) The lateral sector of the dorsal premotor cortex, known to receive both visual and somatosensory input, is the site where neurons retrieve information about both the target and the body part, while subsequent activity specifies the planned action. (2) We found that cells in the ventral premotor cortex primarily reflect the process of information retrieval. On the other hand, cells in the dorsal premotor cortex more often represent the process of integrating the spatial-target and limb-use information, and subsequently of planning an 'action' to take. Such activity was infrequent in medial motor areas. (3) The rostral part of the cingulate motor areas plays a part in processing the reward information for motor selection. (4) Cells in the dorsolateral prefrontal cortex play a role in behavioral planning at the level of categorization, a cognitive level more complex than required for planning individual sequences. (5) On the other hand, cells in the dl-PF take part in retrieving and holding information about the temporal sequence of events for planning subsequent motor behavior. (6) Cells in the inferior parietal lobe are found to reflect the number of actions taken by the subject itself, thereby providing information to select a next action.