Scarpini C, Mazzocchio R, Mondelli M, Nuti D, Rossi A
Institute of Neurological Sciences, University of Siena, Italy.
ORL J Otorhinolaryngol Relat Spec. 1991;53(2):100-5. doi: 10.1159/000276197.
Variations in spinal motoneuron excitability, tested by the monosynaptic H reflex of the soleus muscle, were studied in man in relation to angular acceleration of the body in a damped rotating chair. Clockwise and anticlockwise rotation produced similar changes on the same spinal motoneurons, consisting of a first clear-cut facilitatory phase starting at 0.4 degrees of rotation (corresponding to 156 ms) with a peak between 10 and 30 degrees, followed by a second excitatory phase between 50 and 100 degrees; then, the amplitude of the H reflex progressively recovered to its control value. Both facilitatory phases showed a significant decrease by reducing the angular velocity and acceleration. Control experiments ruled out that both the startle reaction of the subject and variations in the somatosensory input during rotation could be responsible for generating the facilitatory effects on the H reflex. The mean value of the voluntary reaction to turning sensation was 1.1 degrees, corresponding to about 335 ms. It is concluded that the changes described in motoneuron excitability could represent a vestibulospinal reflex response originating from the horizontal semicircular canals.
通过比目鱼肌的单突触H反射测试脊髓运动神经元兴奋性的变化，在人体中研究了其与在阻尼旋转椅中身体角加速度的关系。顺时针和逆时针旋转对相同的脊髓运动神经元产生相似的变化，包括从0.4度旋转（对应156毫秒）开始的第一个明确的易化期，峰值出现在10至30度之间，随后是50至100度之间的第二个兴奋期；然后，H反射的幅度逐渐恢复到其对照值。通过降低角速度和加速度，两个易化期均显示出显著降低。对照实验排除了受试者的惊吓反应和旋转过程中体感输入的变化可能导致对H反射产生易化作用的可能性。对旋转感觉的自主反应的平均值为1.1度，对应约335毫秒。结论是，运动神经元兴奋性的上述变化可能代表源自水平半规管的前庭脊髓反射反应。
