Role for cells in the cingulate motor area of the monkey

本研究的目的是在奖赏评估的基础上，研究扣带回吻侧运动区(CMAR)神经元活动如何参与运动变化。两只猕猴(Macaca Fuscata)被训练成对视觉触发信号(LED)做出两种不同的手臂动作(转动或拉动手柄)。每一个动作都是从中立的姿势开始的。起初，猴子必须猜测两个动作中哪一个是正确的。正确的动作会得到一滴果汁(0.1毫升)作为奖励。在一组试验(5-11次恒定奖励试验)中，正确的动作没有改变，要求猴子保持选择相同的动作。此后，如果猴子重复同样的动作，每次试验的奖励金额将逐步减少30%。在行为时间表的这个阶段，猴子可以自由地选择另一种运动。如果他们做了动作改变，那么另一种动作现在被定义为正确的动作。改写的金额恢复到了最高水平，一系列新的恒定奖励试验开始了。在CMAR中，大约28%的任务相关神经元在奖赏减少的发生和启动与先前执行的动作不同的选定动作之间的一段时间内处于活跃状态。剩余的神经元在运动开始或为下一次运动做准备期间是活跃的。相反，尾侧扣带运动区(CMAC)和初级运动皮质(MI)的细胞主要与运动的执行或运动准备有关。只有少数CMAC细胞(3%)和MI细胞(1%)显示出与运动选择有关的活动。这些观察结果表明，CMAR在运动改变或基于奖赏评估的运动选择中起作用。另一方面，CMAC和MI都不是处理奖赏信息以进行运动选择的皮质部位。

The purpose of the present study was to examine how neuronal activity in the rostral cingulate motor area (CMAr) is involved in the movenent alteration based on the evaluation of reward. Two monkeys (Macaca fuscata) were trained to perform two different arm movements (turn or pull a handle), in response to visual trigger signal (LED). Each movement was started from a neutral position. Initially, the monkey has to guess which of two movements was correct. The correct movement was rewarded with a drop of fruit juice (0.1ml). The correct movememt was not changed during in a block of trials (5-11 trials of constant-reward), requiring the monkeys to keep selecting the same movement. Thereafter, the amount of reward was progressively decreased by 30% per trial, if the monkey repeated the same movement. At this stage of the behavioral time schedule, the monkeys were free to select a alternative movement. If they did movement alteration, the alternative movement was now defined as a correct movement. The amount of reword came back to its full amount, and a new series of the constant-reward trials begun. In CMAr, about 28% of task-related neurons were active during a interval between the occurrence of reduced reward and the initiation of a selected movement that was different from a previously performed movement. Remaining neurons were active in relation to movement initiation or during a period of preparation for a next movement. In contrast, cells in the caudal cingulate motor area (CMAc) and in the primary motor cortex (MI) were mostly related to the execution of movement or motor preparation. Only small number of CMAc cells (3%) and MI cells (1%) exhibited activity related to motor selection. These observations indicate that the CMAr plays a role in motor alteration or motor selection based on the reward evaluation. On the other hand, neither the CMAc and the MI are the cortical sites where the reward information is processed for the purpose of motor selection.