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首页> 外文期刊>Canadian Journal of Physiology and Pharmacology >Rate-coding of spinal motoneurons with high-frequency magnetic stimulation of human motor cortex.
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Rate-coding of spinal motoneurons with high-frequency magnetic stimulation of human motor cortex.

机译：脊髓运动神经元的频率编码与人类运动皮层的高频磁刺激。

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摘要

Rate-coding in spinal motoneurons was studied using high-frequency magnetic stimulation of the human motor cortex. The subject made a weak contraction to cause rhythmic (i.e., tonic) discharge of a single motor unit in flexor (or extensor) carpi radialis or tibialis anterior, while the motor cortical representation of that muscle was stimulated with brief trains of pulses from a Pyramid stimulator (4 Magstim units connected by 3 BiStim modules). An "m@n" stimulus train consisted of m number of pulses (1–4), with an interpulse interval (IPI) of n ms (1–6). Peristimulus time histograms were constructed for each stimulus condition of a given motor unit, and related to the average rectified surface electromyography (EMG) from that muscle. Surface EMG responses showed markedly more facilitation than single-pulse stimulation, with increasing numbers of pulses in the train; responses also tended to increase in magnitude for the longer IPI values (4 and 6 ms) tested. Motor-unit response probabilityincreased in a manner comparable to that of surface EMG. In particular, motoneurons frequently responded twice to a given stimulus train. In addition to recruitment of new motor units, the increased surface EMG responses were, in part, a direct consequence of short-term rate-coding within the tonically discharging motoneuron. Our results suggest that human corticomotoneurons are capable of reliably following high-frequency magnetic stimulation rates, and that this activity pattern is carried over to the spinal motoneuron, enabling it to discharge at extremely high rates for brief periods of time, a pattern known to be optimal for force generation at the onset of a muscle contraction.
机译：使用人类运动皮层的高频磁刺激研究了脊髓运动神经元的速率编码。受试者收缩较弱，导致radial肌（或伸肌）腕pi或胫骨前肌单个运动单位的节律性（即强直性）放电，而该肌肉的运动皮层表现受到来自金字塔的短暂脉冲刺激刺激器（通过3个BiStim模块连接的4个Magstim单元）。 “ m @ n”刺激序列由m个脉冲（1-4）组成，脉冲间隔（IPI）为n ms（1-6）。针对给定运动单元的每种刺激条件构建蠕动时间直方图，并与该肌肉的平均整流表面肌电图（EMG）相关。与单脉冲刺激相比，表面肌电信号的响应显示出明显更多的促进作用，随着列车中脉冲数量的增加。对于较长的IPI值（4和6 ms），响应也趋于增加。运动单位反应的可能性以与表面肌电图相当的方式增加。特别是，运动神经元经常对给定的刺激序列做出两次反应。除了招募新的运动单元外，增加的表面肌电图反应部分是在声放电运动神经元内短期速率编码的直接结果。我们的结果表明，人类皮质激素能够可靠地遵循高频磁刺激速率，并且该活动模式会延续到脊髓运动神经元，使其能够在短时间内以极高的速率放电，这种模式被称为最适合在肌肉收缩时产生力量。

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