Olivocerebellar modulation of motor cortex ability to generate vibrissal movements in rat
Olivocerebellar modulation of motor cortex ability to generate vibrissal movements in rat
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DOI：
10.1113/jphysiol.2005.102764
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发表时间：
2006-02-15
影响因子：
5.5
通讯作者：
Llinás, R
中科院分区：
文献类型：
--
作者：
Lang, EJ;Sugihara, I;Llinás, R
被称为拂动的触须运动是以脉动或非连续的方式产生的，并且包括简短的规则间隔的运动序列。这些有节奏的时序意味着存在周期性发出的运动指令。由于下橄榄（IO）神经元产生周期性同步放电，可以提供潜在的定时信号，这种可能性进行了测试，确定是否橄榄小脑系统调制运动皮层（MCTX）触发的胡须运动大鼠。将电流脉冲串施加到MCtx，并使用高速摄像机记录所产生的晶须运动。诱发的运动模式表现出与振荡电机驱动节奏的存在相一致的属性。特别是，运动幅度显示出对刺激频率的钟形依赖性，峰值在11.5 +/- 2.3 Hz。此外，运动轨迹表现出谐波和亚谐波夹带模式在特定的刺激频率范围内。相比之下，面部神经刺激引起的运动没有表现出这种频率依赖性。为了测试IO是否是振荡器的问题，IO神经元的特性进行了修改，在体内IO内印防己毒素注射，这提高了同步振荡IO活动，并降低其自然频率。随后的变化，诱发的晶须图案与这些药理作用是一致的。此外，在小脑切除大鼠，振荡调制MCTX诱发的运动大大减少，和内IO印防己毒素注射不影响诱发的运动模式。此外，浦肯野细胞复合体尖峰的多电极记录显示了MCtx刺激列车期间橄榄小脑活动与诱发运动模式的时间相关性。总之，结果表明，MCtx产生运动的能力是由橄榄小脑系统中产生的振荡信号调制的。
The vibrissal movements known as whisking are generated in a pulsatile, or non-continuous, fashion and comprise sequences of brief regularly spaced movements. These rhythmic timing sequences imply the existence of periodically issued motor commands. As inferior olivary (IO) neurones generate periodic synchronous discharges that could provide the underlying timing signal, this possibility was tested by determining whether the olivocerebellar system modulates motor cortex (MCtx)-triggered whisker movements in rats. Trains of current pulses were applied to MCtx, and the resulting whisker movements were recorded using a high speed video camera. The evoked movement patterns demonstrated properties consistent with the existence of an oscillatory motor driving rhythm. In particular, movement amplitude showed a bell-shaped dependence on stimulus frequency, with a peak at 11.5 +/- 2.3 Hz. Moreover, movement trajectories showed harmonic and subharmonic entrainment patterns within specific stimulus frequency ranges. By contrast, movements evoked by facial nerve stimulation showed no such frequency-dependent properties. To test whether the IO was the oscillator in question, IO neuronal properties were modified in vivo by intra-IO picrotoxin injection, which enhances synchronous oscillatory IO activity and reduces its natural frequency. The ensuing changes in the evoked whisker patterns were consistent with these pharmacological effects. Furthermore, in cerebellectomized rats, oscillatory modulation of MCtx-evoked movements was greatly reduced, and intra-IO picrotoxin injections did not affect the evoked movement patterns. Additionally, multielectrode recording of Purkinje cell complex spikes showed a temporal correlation of olivocerebellar activity during MCtx stimulus trains to evoked movement patterns. In sum, the results indicate that MCtx's ability to generate movements is modulated by an oscillatory signal arising in the olivocerebellar system.