Somesthetic Functions in Patients with Brain Disease and Normal Subjects

This paper summarizes the results of a series of studies of somatosensory function in normal and brain-diseased subjects that were designed to investigate: (1) neural mechanisms in tactile resolution and masking, and; (2) cerebral dominance and somesthesis. Our results are consistent with the possibility that lateral inhibition effects influence tactile resolution and masking. Additional findings suggest that the physiologic mechanisms involved in tactile masking and obscuration in healthy subjects also mediate the pathologic expressions of these phenomena shown by patients with cerebral disease. Studies of hemispheric dominance and somesthesis have indicated that patients with right hemisphere disease often demonstrate bilateral impairment in tactile perception of direction while this deficit is confined to the right hand of patients with left hemisphere disease. Consistent with the implications of these clinical findings, right-handed normal subjects show a left-hand superiority for tactile perception of direction. Bilateral impairment on a proprioception task was found for patients with unilateral cerebral disease of either hemisphere. However, only patients with right hemisphere lesions were unable to utilize increments in proprioceptive feedback to improve their performance. The results on tactile perception of direction and proprioceptive feedback are interpreted as consistent with findings for other sensory modalities that point to the crucial role of the right hemisphere in spatial aspects of perception