The influence of increased muscle spindle sensitivity on Achilles tendon jerk and H-reflex in relaxed human subjects
The influence of increased muscle spindle sensitivity on Achilles tendon jerk and H-reflex in relaxed human subjects
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DOI：
10.1080/0899022021000037755
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发表时间：
2002-01-01
影响因子：
0.9
通讯作者：
Rossi-Durand, C
中科院分区：
文献类型：
--
作者：
Rossi-Durand, C
根据新数据，重新检查了Fusimotor系统是否有助于强化动作期间反射增益的变化。最近，通过对源自踝屈肌的纺锤体传入活动的直接记录，我们表明，在完全放松的人类受试者中，心理计算增加了肌纺锤体的机械敏感性，而无需伴随α运动神经元激活，为选择性梭运动驱动激活提供了证据。在本研究中，研究了心理计算对通过直接神经刺激（霍夫曼反射，H）或腱敲击（腱反射，T）在非收缩比目鱼肌中引起的单突触反射的影响。目的是将反射大小变化的时间过程与精神任务期间纺锤体敏感性的增加联系起来，以探讨梭运动激活是否可以影响单突触反射的大小。结果显示反射幅度的变化与肌梭敏感性的增加平行。当 T 反射在精神努力过程中持续得到促进时，H 反射要么被抑制，要么被促进，具体取决于受试者。这些发现表明，肌梭初级末梢活动的增加可能是心理计算引起的腱反射和 H 反射变化的原因。 T 反射的促进归因于纺锤体机械敏感性的增强，而 H 反射的抑制归因于 Ia 持续放电增加后的激活后抑制。这项研究支持这样的观点，即肌梭的梭运动敏化是导致机械和电诱发反射变化的原因。结论是，梭运动驱动有助于调整脑力活动期间腱反射和 H 反射的大小。在 H 反射促进的基础上讨论了心理计算任务也可以通过降低突触前抑制水平来进行的可能性。
Whether the fusimotor system contributes to reflex gain changes during reinforcement maneuvers is re-examined in the light of new data. Recently, from direct recordings of spindle afferent activity originating from ankle flexor muscles, we showed that mental computation increased the muscle spindle mechanical sensitivity in completely relaxed human subjects without concomitant alpha-motoneuron activation, providing evidence for selective fusimotor drive activation. In the present study, the effects of mental computation were investigated on monosynaptic reflexes elicited in non-contracting soleus muscle either by direct nerve stimulation (Hoffmann reflex, H) or by tendon tap (Tendinous reflex, T). The aim was to relate the time course of the changes in reflex size to the increase in spindle sensitivity during mental task in order to explore whether fusimotor activation can influence the size of the monosynaptic reflex. The results show changes in reflex amplitude that parallel the increase in muscle spindle sensitivity. When T-reflex is consistently facilitated during mental effort, the H-reflex is either depressed or facilitated, depending on the subjects. These findings suggest that the increased activity in muscle spindle primary endings may account for mental computation-induced changes in both tendon jerk and H-reflex. The facilitation of T-reflex is attributed to the enhanced spindle mechanical sensitivity and the inhibition of H-reflex is attributed to post-activation depression following the increased Ia ongoing discharge. This study supports the view that the fusimotor sensitization of muscle spindles is responsible for changes in both the mechanically and electrically elicited reflexes. It is concluded that the fusimotor drive contributed to adjustment of the size of tendon jerk and H-reflex during mental effort. The possibility that a mental computation task may also operate by reducing the level of presynaptic inhibition is discussed on the basis of H-reflex facilitation.