Department of Biophysics, Ege University, Izmir, Turkey.
Clin Neurophysiol. 2012 Nov;123(11):2192-9. doi: 10.1016/j.clinph.2012.04.005. Epub 2012 May 18.
We studied whether the distribution of synaptic input from compound group I afferents onto the various-sized motoneurons in the human soleus muscle supports the size principle.
The subject lay prone on a physiotherapy table and electrical stimuli were delivered to the tibial nerve. The recordings were taken with surface electromyography (SEMG) and single motor unit (SMU) potentials. The relative sizes of SMUs were estimated using four different methods. After identifying the relative size of each SMU of the pair, normalised size of the H-reflex was determined using the extra spike per trigger (ESPT) method.
In total 33 SMU pairs were studied to compare results obtained in each pair. It was found that, although the stimulus intensity was identical for each pair, the ESPT values were statistically larger in the bigger SMUs compared with the relatively smaller SMUs (p<0.05).
We conclude that, within the limits of this study, compound group I excitatory input to soleus motoneurons in human subjects does not support the size principle which governs the recruitment order of motoneurons in the reduced animal preparations.
This study illustrates the importance of performing human experiments to confirm or reject principles obtained using reduced animal preparations.
我们研究了复合 I 群传入纤维对人比目鱼肌中各种大小的运动神经元的突触传入分布是否支持大小原则。
受试者俯卧在理疗台上，用电刺激胫神经。记录采用表面肌电图（SEMG）和单个运动单位（SMU）电位。使用四种不同的方法估计 SMU 的相对大小。在确定对的每个 SMU 的相对大小后，使用额外的触发脉冲数（ESPT）方法确定 H 反射的归一化大小。
总共研究了 33 对 SMU 对，以比较每对得到的结果。结果发现，尽管对每一对的刺激强度相同，但与相对较小的 SMU 相比，ESPT 值在较大的 SMU 中具有统计学意义（p<0.05）。
我们的结论是，在本研究的范围内，复合 I 群兴奋性传入到人类比目鱼肌运动神经元并不支持支配减少动物标本中运动神经元募集顺序的大小原则。
这项研究说明了进行人体实验以确认或否定使用减少动物标本获得的原理的重要性。
