BEHAVIORAL DEFICITS REVEALED BY MULTIPLE TESTS IN RATS WITH ISCHEMIC DAMAGE LIMITED TO HALF OF THE CA1 SECTOR OF THE HIPPOCAMPUS

Ischemia causes neuronal necrosis in the septal half of the CA1 sector of the hippocampus in rats and produces deficits in spatial and other tasks, but the impairments are not severe. CA1-damaged rats may perform at control levels on some tests and may overlap the performance of control animals on other tests. The present study examined the performance of CA1-damaged rats on a range of tests known to be sensitive to hippocampal damage and evaluated the size of the deficit using a composite test-battery score. The rats with CA1 damage were impaired on learning set, matching to place, and latent-learning spatial navigation in a swimming pool, delayed alternation, and pattern alternation on dry land, but not on amphetamine-induced locomotion or on negative patterning. The CA1-damaged rats' impairments were mild, characterized by behavioral strategies similar to those of control rats, and their test scores overlapped those of control rats. Nevertheless, a composite profile derived from the measures obtained from the different tests revealed a large overall impairment. The results confirm that rats with partial damage to CA1 display impairments, especially on tests that demand working memory, and suggest that the test-battery approach can be used to enhance group differences.