Contralateral somatosensory neglect in unrestrained rats after lesion of the parietal cortex of the left hemisphere

Abstract

Three groups of rats were studied: a sham operated control group and two groups in which the parietal association cortex had been ablated in the left and right hemispheres respectively. Twenty-four hours and 8 days postoperatively the animals were subjected to a test in which their responsiveness to lateralized somatosensory stimuli was measured while the rats were left unrestrained. Additionally, an activity cage locomotion test followed immediately upon both tests of somatosensory responsiveness. Twenty-four hours postoperatively the animals in which the parietal cortex of the left hemisphere had been ablated demonstrated a significant contralateral neglect of somatosensory stimuli while the group in which the right parietal cortex had been ablated only exhibited a non-significant tendency to a contralateral neglect. While the activity cage test did not reveal an overall difference in the activity level of the three groups the latency to initiate locomotion in the activity cage was found to be significantly decreased in both ablated groups. Eight days postoperatively both ablated groups appeared fully recovered. It is concluded that ablations of the parietal association cortex of the rat are associated with a syndrome of contralateral somatosensory neglect that can even be demonstrated if the animals are left unrestrained during testing