先行抑制の運動パターンpresetting依存性の検討

抄録

Many studies have been conducted on the monosynaptic reflex (H-reflex) changes which occur before a voluntary movement in man. Especially, it has been shown that there were the changes of H-reflex prior to the rapid plantarflexion movement which was called the premotor inhibition.
In the present study, the changes in soleus H-reflex prior to a choice reaction time (RT) were studied, giving the special attention to the possible functional difference of motor patterns to generate the premotor inhibition during a period when the physiological mechanisms involved in the movement.
The changes of H-reflex were measured in choice RT experiment in 9 and 6 male subjects under the different two conditions : (a) selection of the response sides (left or right plantarflexion) -the movement pattern was known before the presentation of a response signal ; and (b) selection of the movement patterns (plantar or dorsiflexion) -the responce side was known before.
The premotor inhibition was observed only in case of (a), and was dependent on a prerequisite for movement patterns. Moreover, the physiological significance of this phenomenon was indeed related to a presynaptic inhibition, and was related to a modulation of alpha-motoneurone excitability by the pyramidal system. Thus, the premotor inhibition might be related to central motor preprogram controlling presynaptic inhibition on the reflex pathways.