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首页> 外文期刊>The European Journal of Neuroscience >Mechanical and focal electrical stimuli applied to the skin of the index fingertip induce both inhibition and excitation in low-threshold flexor carpi radialis motor units.
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Mechanical and focal electrical stimuli applied to the skin of the index fingertip induce both inhibition and excitation in low-threshold flexor carpi radialis motor units.

机译：对食指指尖皮肤施加的机械和聚焦电刺激在低阈值屈肌腕radial运动单元中引起抑制和激发。

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摘要

It has been observed that mechanical stimulation of the skin of the index fingertip causes a weak short-latency inhibition followed by a strong long-lasting facilitation of the flexor carpi radialis (FCR) H-reflex. Based on threshold and latency, these cutaneous reflexes are thought to be routed to motoneurons by parallel pathways. As recent studies have shown predominant inhibitory potentials in slow motoneurons and predominant excitatory potentials in faster ones, the question arises as to whether or not the two cutaneous pathways converge onto the same motoneuron. The poststimulus time histogram technique was used to investigate the changes in firing frequency of low-threshold FCR motor units (MUs), induced by passive mechanical or focal electrical stimuli to the index skin. After gently tapping the finger pulp a small sharp inhibition appeared in 20 MUs. On average, inhibition started 10.2 +/- 1.6 ms from the homonymous Ia monosynaptic effect, and its central delay was estimated to be 1.2 +/- 1.6 ms. The subsequent facilitation, more consistent, had a mean latency of 13.5 +/- 1.7 ms. Inhibition and excitation were statistically significant (P < 0.05). A similar biphasic effect was observed in seven other FCR-MUs, also after focal electrical stimulation of the same skin area. Comparison with the time course of the H-reflex, representing the whole population of MUs, showed striking similarities in time course and latency to the present MU effect. It is thus suggested that cutaneous spinal pathways may have a homogeneous distribution within the FCR motoneuron pool, and that the skewed distribution of cutaneous afferents onto motoneurons should be not taken as a rule.
机译：已经观察到，食指皮肤的机械刺激引起弱的短时延抑制，然后强烈地促进了radial侧腕屈肌（FCR）H-反射。基于阈值和潜伏期，这些皮肤反射被认为是通过平行途径传导至运动神经元的。由于最近的研究表明慢运动神经元具有主要的抑制潜力，而较快运动神经元具有主要的兴奋潜力，因此出现了两个皮肤途径是否会汇聚到同一运动神经元上的问题。刺激后时间直方图技术用于研究低阈值FCR运动单元（MUs）的发动频率变化，该变化是由被动机械或聚焦电刺激对皮肤产生的。轻轻敲打指腹后，在20 MU中出现了小的尖锐抑制。平均而言，抑制作用始于同音Ia单突触作用的10.2 +/- 1.6毫秒，估计其中心延迟为1.2 +/- 1.6毫秒。随后的协调更加一致，平均等待时间为13.5 +/- 1.7毫秒。抑制和兴奋具有统计学意义（P <0.05）。在对相同皮肤区域进行局部电刺激后，在其他七个FCR-MU中也观察到了类似的双相效应。与代表整个MU人群的H反射的时程进行比较，显示出时程和潜伏期与当前MU效果具有惊人的相似性。因此，建议在FCR运动神经元池中皮肤脊柱通路可能具有均匀分布，并且不应将皮肤传入神经元在运动神经元上的偏斜分布作为规则。

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