Nonsensory neglect from parietotemporal lesions in monkeys

Monkeys trained to perform with the extremity contralateral to a stimulus had unilateral neglect induced by a parietotemporal lesion. Their performance was normal postoperatively when stimulated on the side contralateral to the lesion, but they made errors when stimulated on the normal side (the side ipsilateral to the lesion), often failing to use the extremity on the neglected side (the side contralateral to the lesion). Although we expected parietotemporal lesions to induce sensory neglect (failure to respond to contralateral stimuli), we could show only that these animals had a defect of intention (contralateral hypokinesia). In this respect, neglect induced by parietotemporal lesions is similar to that induced by frontal or medial thalamic lesions.