The effects of unilateral ablation of the cortical motor forelimb area on instrumental avoidance responses consisting of lifting the forelimb and holding it within a 4 cm wide "safety zone" were studied in dogs. It was found that the surgery irreversibly impaired the search for the safety zone, while the ability to maintain the limb at a certain height was not affected. The surgery also impaired the corrective movements, especially if their direction was opposite to the inborn unconditioned

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... tion. The ability to perform corrective movements of small amplitude was also transiently diminished Widening of the safety zone markedly improved the post-operative performance.