Impaired spatial performance in rats with retrosplenial lesions: Importance of the spatial problem and the rat strain in identifying lesion effects in a swimming pool

Behavioral, electrophysiological, and anatomical evidence sug-gests that retrosplenial (RS) cortex (areas RSA and RSG) plays a role in spatial navigation. This conclusion has been ques-tioned in recent work, suggesting that it is damage to the underlying cingulum bundle (CG) (areas CG and IG), and not RS, that disrupts spatial place learning (Aggleton et al., 2000). We revisited this issue by comparing Long–Evans rats, the strain used in studies that report RS deficits, to Dark Agouti rats, the strain in which no RS deficit has been reported. Rat groups with RS, RS CG, or no lesion were tested on a place task in a swimming pool, a test of nonspatial and spatial learning, and a matching-to-place task, a relatively selective test of spatial learning. Long–Evans rats given RS and RS CG lesions, either before or after training on the two tasks, were impaired on both tasks, a deficit not attributable to impaire