Self-sustained firing of human motor units
Self-sustained firing of human motor units
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DOI：
10.1016/s0304-3940(98)00277-8
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发表时间：
1998-05-08
影响因子：
2.5
通讯作者：
Yang, JF
中科院分区：
文献类型：
--
作者：
Gorassini, MA;Bennett, DJ;Yang, JF
无脊椎动物和脊椎动物的运动神经元在被短暂的兴奋性突触输入(自我维持的放电)激活后，可以继续重复放电。这种放电行为是由于固有的电压门控电流的激活，这些电流产生了细胞持续的再生去极化(平台电位)。对这些固有细胞特性的检查已经在减少的动物制剂中进行，尚不清楚II这种自我维持的放电发生在完好无损的人的运动神经元中。在这篇文章中，我们通过使用双运动单位记录技术在人类中提供了这方面的证据。受试者被指示保持恒定的背屈运动，并通过记录低阈值控制单位的放电频率来监测到胫骨前运动神经元池的共同突触输入(例如，下行驱动)。一旦控制单位的放电频率是恒定的，TA肌腱的振动就会招募第二个“测试”单位，该单位在振动(即突触输入)被移除后继续激发，即使控制单位的放电速率(以及共同驱动)保持不变或降低。当需要持续的肌肉激活(例如，姿势紧张)时，像这样的运动神经元的自我持续放电可以减少对长时间突触输入的需要。(C)1998年爱思唯尔爱尔兰科学有限公司。
Motoneurons of invertebrates and vertebrates can continue to fire repetitively after being activated by a brief, excitatory synaptic input (self-sustained firing). This firing behavior is due to the activation of intrinsic, voltage-gated currents which produce sustained regenerative depolarizations (plateau potentials) of the cell. Examination of these intrinsic cellular properties has been performed in reduced animal preparations and it is unknown ii such self-sustained firing occurs in motoneurons of the intact human. In this paper, we present evidence of this in the human by using a technique of dual motor unit recordings. Subjects were instructed to maintain a constant dorsiflexion effort, and the common synaptic input (e.g. descending drive) onto the tibialis anterior (TA) motoneuron pool was monitored by recording the firing frequency of a low threshold 'control' unit. Once the firing rate of the control unit was constant, vibration of the TA tendon recruited a second 'test' unit which continued to fire after the vibration (i.e. synaptic input) was removed, even though the firing rate of the control unit (and thus, the common drive) remained the same or decreased. Self-sustained firing of motoneurons such as this may reduce the need for prolonged synaptic input when constant muscle activation is required (e.g. for postural tone). (C) 1998 Elsevier Science Ireland Ltd.