Ohbayashi Machiko, Picard Nathalie, Strick Peter L
Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh Brain Institute, and Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261.
Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh Brain Institute, and Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
J Neurosci. 2016 Feb 10;36(6):1971-6. doi: 10.1523/JNEUROSCI.2356-15.2016.
As skill on a sequence of movements is acquired through practice, each movement in the sequence becomes seamlessly associated with another. To study the neural basis of acquired skills, we trained two monkeys (Cebus apella) to perform two sequential reaching tasks. In one task, sequential movements were instructed by visual cues, whereas in the other task, movements were generated from memory after extended practice. Then, we examined neural activity in the dorsal premotor area (PMd) and the effects of its local inactivation during performance of each task. Comparable numbers of neurons in the PMd were active during the two tasks. However, inactivation of the PMd had a marked effect only on the performance of sequential movements that were guided by memory. These results emphasize the importance of the PMd in the internal generation of sequential movements, perhaps through maintaining arbitrary motor-motor associations.
The dorsal premotor cortex (PMd) has long been thought to be a critical node in the cortical networks responsible for visually guided reaching. Here we show that PMd neurons are active during both visually guided and internally generated sequential movements. In addition, we found that local inactivation of the PMd has a marked effect only on the performance of sequential movements that were internally generated. These observations suggest that, although the PMd may participate in the generation of visually guided sequences, it is more important for the generation of internally guided sequences.
随着通过练习掌握一系列动作的技能，序列中的每个动作都与另一个动作无缝关联。为了研究习得技能的神经基础，我们训练了两只猴子（僧帽猴）执行两项连续的伸手任务。在一项任务中，连续动作由视觉线索指示，而在另一项任务中，动作是在长时间练习后从记忆中产生的。然后，我们检查了背侧运动前区（PMd）的神经活动及其在每项任务执行过程中的局部失活效应。在两项任务中，PMd中活跃的神经元数量相当。然而，PMd的失活仅对由记忆引导的连续动作的表现有显著影响。这些结果强调了PMd在连续动作的内部生成中的重要性，可能是通过维持任意的运动-运动关联。
长期以来，背侧运动前皮质（PMd）一直被认为是负责视觉引导伸手的皮质网络中的关键节点。在这里我们表明，PMd神经元在视觉引导和内部生成的连续动作中均活跃。此外，我们发现PMd的局部失活仅对内部生成的连续动作的表现有显著影响。这些观察结果表明，尽管PMd可能参与视觉引导序列的生成，但它对内部引导序列的生成更为重要。
