Forelimb muscle contraction induced by cerebral cortical stimulation after callosotomy: a myographic study in the mouse.

The effect of callosotomy upon motor control by the cerebral cortex on the forelimb was examined in the mouse. On the 10th day after callosotomy in the rostral or caudal part of the corpus callosum, the forelimb area of the cerebral motor cortex was stimulated intracortically with a microelectrode and muscle contraction of the forelimb was recorded by electromyography. Muscle contraction was observed in the contralateral forelimb in the mice of which callosal fibers were cut in the caudal part of the corpus callosum including the splenium corporis callosi as well as in the normal mice. On the other hand, muscle contraction was observed in the ipsilateral forelimb in the mice of which callosal fibers were incised in the rostral part of the corpus callosum including the genu, rostrum and trunk. The latency of the muscle contraction was about 0.5 msec in the both groups of the callosotomized mice, as well as in the normal mice.