RELATIONSHIP BETWEEN ALPHA-BLOCKING AND SLOW POTENTIAL CHANGES PRECEDING REACTION MOVEMENT

Abstract

In order to investigate the association of alpha-blocking with motor set under the condition of simple reaction movement, the scalp distribution of alpha wave envelope recorded by averaging method was compared with that of slow potential changes. The results were as follows.
1) The slow potential changes (readiness potential, early and late component of CNV) were large over the central and frontal area. The readiness potential was larger over the contralateral than the ipsilateral central motor area, while the early component of CNV showed bilateral spread. The late component of CNV showed the similar scalp distribution to that of readiness potential, but the latter was much more lateralized.
2) The alpha-blocking was bilaterally symmetrical over the central and occipital area under the condition of photic stimulus without movement. But the alpha-blocking accompanying preparatory signal increased over the frontal and central area compared with control alpha-blocking, and was larger over the contralateral than ipsilateral central motor area.
3) The maximal alpha-blocking rate showed to correlate negatively with its latency under each condition. The difference in alpha-blocking rate at the onset of the imperative stimulus between reaction movement and control showed to correlate negatively with reaction time.
From these findings, it seems that alpha-blocking accompanying preparatory signal reflects not only input system but also readiness potential component, and that in temporal respect alpha-blocking increases at the onset of movement.