INTERHEMISPHERIC CONTROL OF MANUAL MOTOR-ACTIVITY

The interhemispheric control of manual motor processes is reviewed, fo cusing on the clinical evidence from patients with commissurotomies an d with agenesis of the corpus callosum. There is little evidence for a role of the corpus callosum in transferring explicit motor commands. Rather, the corpus callosum seems important for transferring lateralis ed information (such as verbal or visuospatial activity) of the pre-mo tor. variety. Also, the corpus callosum may become very significant wh en movement begins: there appears to be a transcallosal passage of cor ollary motor signals and feedback sensory signals that are used to con trol asynchronous bimanual movements and to inhibit the opposite hemis phere from interfering when a simple unimanual movement is required.