[Transcallosal modulation of a focus of maximal activity in the motor cortex]

In cats, EPs from 170 symmetrical points of the motor cortex were recorded during bilateral and unilateral stimulation of nerves of hind--and forelimbs. Charts of localization of the maximal activity foce (MAF) were drawn. Transection of the corpus callosum was shown to be followed by narrowing of MAFs during bilateral stimulation and by their enlargement during unilateral stimulation. The effect of MAF enlargement was found to be due to summation of thalamocortical and transcallosal projections in animals with intact callosal system, while the MAF narrowing effect--to be determined by reciprocal transcallosal influences. Existence of the spatial transcallosal modulation of thalamocortical projection in the motor cortex is supposed.