BILATERAL DESTRUCTION OF THE VENTROLATERAL ORBITAL CORTEX PRODUCES ALLOCENTRIC BUT NOT EGOCENTRIC SPATIAL DEFICITS IN RATS

Previous studies have implicated the ventrolateral orbital cortex (VLO ) in spatial attention and orientation. Unilateral destruction of the VLO has been found to produce severe multimodal neglect to unilateral stimulation which is qualitatively quite similar to that found followi ng unilateral destruction of either the medial agranular or posterior parietal cortices. A series of anatomical studies have shown that the VLO is reciprocally interconnected with both the medial agranular cort ex and the posterior parietal cortex, which are involved in egocentric and allocentric spatial processing respectively. However, the role of the VLO is either egocentric or allocentric spatial processing has ne ver been directly examined. The present study directly examined the ro le of the VLO in spatial learning by examining the effects of bilatera l VLO destruction on performance in both egocentric (adjacent-arm maze task) and allocentric (cheeseboard task) spatial tasks. Subjects in e ither the cheese board task or the adjacent arm maze were given presur gical maze training and then were assigned to one of three surgical gr oups: a bilateral VLO group, a lesion control control group which rece ived bilateral destruction of the laterally adjacent lateral orbital c ortex which has a quite different pattern of connectivity than the VLO , or a sham operated control group. The results indicated that the VLO operates were significantly impaired in the cheeseboard task (allocen tric task) relative to controls, but displayed no deficits in the adja cent-arm maze (egocentric task), a pattern of results similar to those found for the posterior parietal cortex. The results of the present s tudy strongly support the contention that the VLO is a component of th e cortical circuitry for spatial processing in rodents.