[Transcallosal modulation of the focus of maximal activity in the visual cortex]

In cats, EPs on binocular and monocular adequate stimulation in 270 symmetrical points of the visual cortex (the 17, 18, and 19 fields, and the medial portion of the suprasylvian gyrus), were studied. Charts of the maximal activity foci were drawn. Callosal transection was shown to enlarge the foci. The phenomenon of narrowing foci of maximal activity in animals with intact callosal system was found to be due to suppressing (resiprocal) interhemispherical influences increasing from the periphery towards the center of the focus. A spatial transcallosal modulation of the thalamo-cortical activation was suggested to exist in the visual cortex.