Posterior neocortical (visual cortex) lesions in the rat impair matching-to-place navigation in a swimming pool: a reevaluation of cortical contributions to spatial behavior using a new assessment of spatial versus non-spatial behavior.

In the face of contradictory findings on the role of visual cortex contributions to spatial behavior, the present study evaluated the ability of rats with primary visual cortex (Area 17) lesions to learn spatial problems in a swimming pool. Because the solution to any spatial learning problem consists of acquiring at least two primary elements of a task, task procedures and spatial learning, the study, in addition to assessing spatial ability on a place task, used two training/testing methods to identify the nature of the spatial impairment associated with visual cortex lesions. Non-spatial training consisted of learning to find a platform in the dark and spatial training consisted of a series of matching-to-place problems. The results confirmed that although rats with visual cortex lesions were impaired on place learning, the deficit was partially ameliorated by non-spatial training given following the lesion, and completely ameliorated by non-spatial training given before the lesion. Nevertheless, all visual cortex groups failed to show a quadrant preference on a probe trial and displayed a profound impairment in matching-to-place learning. This definitive demonstration that appropriate testing methods can reveal a failure in spatial behavior following visual cortex lesions is consistent with the idea that primary visual cortex is required in spatial navigation.