ACUTE AND CHRONIC PARIETAL LOBE ABLATIONS IN MONKEYS

Abstract

Acute and chronic parietal ablations were made in the macaque. Area 3, areas 1-2, area 5 and area 7 were removed individually and areas 1-2, 5, and 7 in combination. No paralyses resulted but instead there was present a loathness for movement. Removal of area 3 or of areas 1-2 affected the contralateral arm and leg equally; of area 5, particularly the leg and of area 7, the arm. Hypotonia was consistently present for as long as a yr., but not equally so in all contralateral muscle groups. Ataxia was not present when movement was checked by vision. Tendon reflexes were permanently altered. Muscle atrophy, and hyperpathia were observed in one chronic animal after removal of areas 1-2, 5, and 7 together. Appreciation of tactile and painful stimuli were impaired initially after all ablations and for 9 mos. after postcentral lesions. Localization was persistently lost. The postcentral gyrus was necessary for recognition and all parietal areas for localization and discrimination. Proprioceptive placing and hopping and tactile placing were lost immediately after all ablations; the first 2 returned after 3 wks.; the last was never normal after postcentral lesions. Response was slow after return following removal of areas 5 and 7.