Cortical control of a whisking central pattern generator
Cortical control of a whisking central pattern generator
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DOI：
10.1152/jn.00071.2006
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发表时间：
2006-07-01
影响因子：
2.5
通讯作者：
Keller, Asaf
中科院分区：
文献类型：
--
作者：
Cramer, Nathan P.;Keller, Asaf
运动皮层是通过直接生成运动模式还是通过皮层下中央模式发生器（CPG）来调节自主运动仍然是运动控制的核心问题。利用大鼠胡须系统（哺乳动物运动控制的重要模型系统），我们开发了一种麻醉制剂来研究运动皮层和搅拌 CPG 之间的相互作用。使用该模型，我们研究了搅拌 CPG 的血清素能成分在确定搅拌运动学中的作用，以及将 CPG 的驱动力转化为触须运动单元运动的机制。与触须运动皮层 (vMCx) 对皮层下 CPG 的作用一致，vMCx 皮质内微刺激 (ICMS) 引起的拂动频率与刺激频率显着不同，而拂动起始潜伏期与刺激强度呈负相关。此外，ICMS 诱发的搅拌被血清素受体拮抗剂抑制，这支持了之前的研究结果，即搅拌 CPG 含有重要的血清素能成分。 ICMS 诱发的搅拌幅度与活动运动单位的数量（从触须肌电图分离或直接从触须运动神经元记录）及其活动水平相关。此外，搅拌频率与这些运动神经元的放电率相关。这些发现支持了这样的假设：vMCx 通过其对皮层下 CPG 的作用来调节搅拌。
Whether the motor cortex regulates voluntary movements by generating the motor pattern directly or by acting through subcortical central pattern generators (CPGs) remains a central question in motor control. Using the rat whisker system, an important model system of mammalian motor control, we develop an anesthetized preparation to investigate the interaction between the motor cortex and a whisking CPG. Using this model we investigate the involvement of a serotonergic component of the whisking CPG in determining whisking kinematics and the mechanisms through which drive from the CPG is converted into movements by vibrissa motor units. Consistent with an action of the vibrissa motor cortex (vMCx) on a subcortical CPG, the frequency of whisking evoked by intracortical microstimulation (ICMS) of vMCx differed significantly from the stimulation frequency, whereas whisking onset latencies correlated negatively with stimulation intensity. Further, ICMS-evoked whisking was suppressed by a serotonin receptor antagonist, supporting previous findings that the whisking CPG contains a significant serotonergic component. The amplitude of ICMS-evoked whisking was correlated with the number of active motor units - isolated from vibrissal EMGs or recorded directly from vibrissa motoneurons - and their activity level. In addition, whisking frequency was correlated with the firing rate of these motoneurons. These findings support the hypothesis that vMCx regulates whisking through its actions on a subcortical CPG.