Rossi A, Mazzocchio R, Parlanti S
Laboratorio di Neurofisiologia, Università di Siena, Italy.
Brain Res. 1991 Apr 26;547(1):62-8. doi: 10.1016/0006-8993(91)90574-f.
The possibility was investigated that impulses in group Ib afferents from fore-arm flexors have access to cerebral cortex in man. A long-lasting increase in the threshold (Th) of group Ia afferent fibres from flexor carpi radialis muscle (Fcr) was obtained after prolonged (100 Hz for 20 min) tendon vibration at the wrist. It was assumed that under this condition a weak electrical stimulation of the median nerve at the elbow, insufficient to reactivate Ia fibres because of the rise in their threshold (as verified by the method of homonymous Ia facilitation of Fcr H reflex), engaged Ib fibres only. Peripheral volleys at Erb's point and cerebral cortical potentials to median nerve stimulation at the elbow were evoked before and after prolonged vibration of Fcr. During 10-30 min after the end of vibration, in which homonymous facilitation of Fcr H reflex was abolished, both the ongoing peripheral volley and the cortical responses were markedly reduced with respect to their control values. Recovery to pre-vibration control amplitudes coincided with recovery of Fcr H reflex homonymous facilitation. In order to verify if activity in afferents other than group Ib fibres might contribute to the cortical response after vibration, specially designed experiments were also performed. It is concluded that the cortical wave recorded after 20 min vibration represents the arrival of Ib impulses from flexor carpi radialis to the human cerebral cortex.
研究了来自前臂屈肌的Ib类传入神经冲动进入人类大脑皮层的可能性。在手腕处进行长时间（100赫兹，持续20分钟）的肌腱振动后，桡侧腕屈肌（Fcr）的Ia类传入纤维阈值（Th）出现了持续增加。假设在这种情况下，在肘部对正中神经进行弱电刺激，由于其阈值升高，不足以重新激活Ia纤维（通过Fcr H反射的同名Ia易化方法验证），此时仅激活了Ib纤维。在Fcr长时间振动前后，分别诱发了Erb点的外周波和肘部正中神经刺激的大脑皮层电位。在振动结束后的10 - 30分钟内，Fcr H反射的同名易化被消除，在此期间，正在进行的外周波和皮层反应相对于其对照值均明显降低。恢复到振动前的对照幅度与Fcr H反射同名易化的恢复相一致。为了验证除Ib类纤维外的其他传入神经活动是否可能对振动后的皮层反应有贡献，还进行了专门设计的实验。得出的结论是，20分钟振动后记录到的皮层波代表了来自桡侧腕屈肌的Ib冲动到达人类大脑皮层。
