Specific cerebral activations induced by unilateral tactile discrimination of macrogeometric objects were identified in positron emission tomography images of regional cerebral blood flow in patients recovered from hemiplegic stroke and in healthy volunteers. Primary sensorimotor cortex, supplementary motor area, superior parietal lobule contralateral to moving hand, and premotor cortex on both sides were regularly activated in normals contrary to patients showing consistent activations only in the primary sensorimotor cortex. Furthermore, areas of activations in parietal association, premotor and midfrontal cortical areas were far less consistently activated in patients than in healthy subjects. These results demonstrated in correspondence to the clinical observations that the patients had regained their ability to move the fingers of the affected hand but remained impaired in tactile discrimination.