Carpenter A F, Georgopoulos A P, Pellizzer G
Brain Sciences Center, Veterans Affairs Medical Center, Minneapolis MN 55417, USA.
Science. 1999 Mar 12;283(5408):1752-7. doi: 10.1126/science.283.5408.1752.
The neural encoding of serial order was studied in the motor cortex of monkeys performing a context-recall memory scanning task. Up to five visual stimuli were presented successively on a circle (list presentation phase), and then one of them (test stimulus) changed color; the monkeys had to make a single motor response toward the stimulus that immediately followed the test stimulus in the list. Correct performance in this task depends on memorization of the serial order of the stimuli during their presentation. It was found that changes in neural activity during the list presentation phase reflected the serial order of the stimuli; the effect on cell activity of the serial order of stimuli during their presentation was at least as strong as the effect of motor direction on cell activity during the execution of the motor response. This establishes the serial order of stimuli in a motor task as an important determinant of motor cortical activity during stimulus presentation and in the absence of changes in peripheral motor events, in contrast to the commonly held view of the motor cortex as just an "upper motor neuron."
在执行情境回忆记忆扫描任务的猴子的运动皮层中，对序列顺序的神经编码进行了研究。多达五个视觉刺激相继呈现在一个圆圈上（列表呈现阶段），然后其中一个（测试刺激）改变颜色；猴子必须对列表中紧跟测试刺激之后的刺激做出单一的运动反应。此任务中的正确表现取决于刺激呈现期间对其序列顺序的记忆。研究发现，在列表呈现阶段神经活动的变化反映了刺激的序列顺序；刺激呈现期间刺激序列顺序对细胞活动的影响至少与运动反应执行期间运动方向对细胞活动的影响一样强烈。这确立了运动任务中刺激的序列顺序作为刺激呈现期间运动皮层活动的一个重要决定因素，且在外周运动事件无变化的情况下，这与将运动皮层仅仅视为“上运动神经元”的普遍观点形成对比。
