Modulation of presynaptic inhibition of Ia afferents during voluntary wrist flexion and extension in man
Modulation of presynaptic inhibition of Ia afferents during voluntary wrist flexion and extension in man
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DOI：
10.1007/s002210000662
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发表时间：
2001-03-01
影响因子：
2
通讯作者：
Raoul, S
中科院分区：
文献类型：
--
作者：
Aymard, C;Baret, M;Raoul, S
在正常人受试者在休息时和自愿的腕关节屈曲和伸展时，Ia终末指向桡侧腕屈肌（FCR）运动神经元（MN）的突触前抑制的变化进行了研究。为此，使用了两种独立的方法：（1）放射诱导的FCR H反射的D1抑制，其评估PAD的兴奋性（初级传入去极化）控制Ia终末突触前抑制的中间神经元介导FCR H反射的传入齐射;（2）刺激内源性肌Ia传入在FCR H反射中诱导的异源性单突触Ia易化，其评估了Ia终末的持续突触前抑制。相对于结果在休息时，它被发现，在发病时（和在强直）自愿腕关节屈曲，D1抑制减少和异源单突触Ia促进增加。这表明，在下肢，突触前抑制减少Ia终端投射到参与自主收缩的MN。相反。在下肢中观察到的结果还发现，在涉及拮抗性腕伸肌的自主收缩开始时，Ia终末对FCR MN的突触前抑制减少，这表明投射到腕屈肌和腕伸肌的Ia终末的突触前抑制可能通过PAD中间神经元的相同子集介导。这与其他特征一致，这些特征表明腕屈肌和伸肌之间的反射通路的组织不同于在其他（肘、踝）关节处观察到的。
Changes in presynaptic inhibition of Ia terminals directed to flexor carpi radialis (FCR) motoneurones (MNs) were investigated in normal human subjects at rest and during voluntary wrist flexion and extension. To that end, two independent methods were used: (1) the radial-induced D1 inhibition of the FCR H reflex, which assesses the excitability of PAD (primary afferent depolarisation) interneurones controlling presynaptic inhibition of Ia terminals mediating the afferent volley of the FCR H reflex; and (2) the heteronymous monosynaptic Ia facilitation induced in the FCR H reflex by intrinsic muscle Ia afferent stimulation, which assesses the ongoing presynaptic inhibition of Ia terminals. With respect to results at rest, it was found that at the onset of (and during tonic) voluntary wrist flexion, D1 inhibition was reduced and heteronymous monosynaptic Ia facilitation was increased. This suggests that, as in the lower limb, presynaptic inhibition is decreased on Ia terminals projecting to MNs involved in the voluntary contraction. In contrast. with results observed in the lower limb, presynaptic inhibition of Ia terminals to FCR MNs was also found to be reduced at the onset of a voluntary contraction involving the antagonistic wrist extensors, suggesting that presynaptic inhibition of Ia terminals projecting to wrist flexors and extensors might be mediated through the same subsets of PAD interneurones. This is in keeping with other features showing that the organisation of reflex pathways between wrist flexors and extensors differs from that observed at other (elbow, ankle) joints.