From the late 1800s until approximately the middle of the 20th century, neurosurgeons made discrete motor cortex lesions in humans in attempts to reduce or eliminate a variety of involuntary movements, resulting mainly from epilepsy. In some cases, the neurosurgeons tested and recorded their patients' ability to perform various movements and to perceive various types of sensory stimuli after the operation. Although these studies have been largely forgotten, they have an immense advantage over primate lesion studies for understanding the function of the motor cortex because the patients were able to attempt to perform complex movements upon request, and to describe their perceptions of cutaneous stimuli, including integrated sensations (e.g., recognition of objects by palpation alone). We provide here a table containing the results of these studies pertaining to sensory deficits. The most consistent and persistent sensory deficits reported relate to object recognition and position sense. This finding is in keeping with recent electrophysiological studies in primates. Our analysis suggests that the “motor” cortex serves important sensory functions; hence, the term sensorimotor cortex, remains appropriate for the primate precentral (and postcentral) cortex.
Joel A. Vilensky and Sid Gilman
Joel A. Vilensky and Brian L. O'Connor
In this paper we review the literature on stepping in nonhuman and human primates with complete transection of the spinal cord and consider these data relative to the principle of “encephalization” of motor functions with ascension in phylogeny. We conclude that techniques useful for producing self-generated stepping behavior in nonprimates with complete spinal cord transection may not be successful in humans and other higher primates with complete transection.