Somaesthetic Alternation,Discrimination and Orientation after Frontal and Parietal Lesions in Monkeys

Eight naïve monkeys were trained on non-visual tests of alternation and discrimination. These animals were also taught to perform a test of orientation with or without visual control. Four animals then received bilateral frontal excisions and three (of four) animals survived bilateral removal of the posterior parietal region. Following surgery, all frontal operates were found to be severely impaired on the somaesthetic alternation test. The parietal operates, on the other hand, were unimpaired on this test though all gave evidence of defective orientation in space. Some implications of the results are discussed.