Yamanaka K, Yamamoto S, Nakazawa K, Yano H, Suzuki Y, Fukunaga T
Motor Dysfunction Division, Research Institute, National Rehabilitation Center for the Disabled, Saitama, Japan.
Neurosci Lett. 1999 May 7;266(2):101-4. doi: 10.1016/s0304-3940(99)00284-0.
H-reflex and motor evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) in soleus muscle of five normal subjects were investigated before and after 20 days 6 degree head-down bed rest (BR). Soleus H-reflex during standing following bed rest decreased in all five subjects. The size of the maximum H-reflex (Hmax), expressed as a percentage of the maximum M-response (Mmax), decreased from 63.3+/-23.3% before BR to 26.7+/-12.5% after BR. However, there were no significant differences between MEPs before and after bed rest. Moreover, MEP/Hmax after bed rest was larger than before bed rest in all subjects. These results indicate a strong inhibition of H-reflex and no adaptation of MEP in soleus muscle during standing following bed rest.
