Rank-order-selective neurons form a temporal basis set for the generation of motor sequences.
Rank-order-selective neurons form a temporal basis set for the generation of motor sequences.
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DOI：
10.1523/jneurosci.0164-09.2009
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发表时间：
2009-04-08
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通讯作者：
Salinas E
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作者：
Salinas E
许多行为都是由一系列必须以特定顺序发生的基本运动动作组成的，但对产生这些运动序列的神经机制却知之甚少。特别是，如果一个序列由几个运动动作组成，灵长类动物可以在练习几次之后学会从记忆中复制它。大脑的运动区和运动前区是如何如此快速地组装运动序列的？这里提出的网络模型揭示了这个问题的部分解决方案。该模型是基于实验表明，在运动序列的性能，一些皮层神经元总是在特定的时间被激活，无论运动动作正在执行。在该模型中，一群这样的等级顺序选择性（ROS）细胞驱动一层下游运动神经元，使它们在不同的时间以不同的顺序产生特定的运动。该模型的一个关键因素是ROS反应的幅度必须由序列同一性来调节。由于这种调制，这与实验报告一致，网络不仅能够准确地产生多个序列，而且能够以最小的连接变化学习新序列。因此，由序列同一性调制的ROS神经元充当用于构建下游运动反应的任意序列的基础集。基本机制类似于顶骨区域中描述的用于在空间域中生成坐标变换的机制。
Many behaviors are composed of a series of elementary motor actions that must occur in a specific order, but the neuronal mechanisms by which such motor sequences are generated are poorly understood. In particular, if a sequence consists of a few motor actions, a primate can learn to replicate it from memory after practicing it for just a few trials. How do the motor and premotor areas of the brain assemble motor sequences so fast? The network model presented here reveals part of the solution to this problem. The model is based on experiments showing that, during the performance of motor sequences, some cortical neurons are always activated at specific times, regardless of which motor action is being executed. In the model, a population of such rank-order-selective (ROS) cells drives a layer of downstream motor neurons so that these generate specific movements at different times in different sequences. A key ingredient of the model is that the amplitude of the ROS responses must be modulated by sequence identity. Because of this modulation, which is consistent with experimental reports, the network is able not only to produce multiple sequences accurately but also to learn a new sequence with minimal changes in connectivity. The ROS neurons modulated by sequence identity thus serve as a basis set for constructing arbitrary sequences of motor responses downstream. The underlying mechanism is analogous to the mechanism described in parietal areas for generating coordinate transformations in the spatial domain.