PROGRESSIVE ENTORHINAL CORTEX LESIONS ACCELERATE HIPPOCAMPAL SPROUTING AND SPARE SPATIAL MEMORY IN RATS

Accelerating hippocampal spouting by making unilateral progressive les ions of the entorhinal cortex spared the spatial memory of rats tested for retention of a learned task. Subsequent transection of the sprout ed crossed temporodentate pathway (CTD), as well as a simultaneous CTD transection and progressive entorhinal lesion, produced a persistent deficit on the memory task. These results suggest that CTD sprouting, which is homologous to the original perforant path input to the dentat e gyrus of the hippocampus, is behaviorally significant and can amelio rate at least some of the memory deficits associated with hippocampal deafferentation.