Bilateral vestibular deafferentation impairs performance in a spatial forced alternation task in rats

Converging behavioral, electrophysiological, and neurochemical data suggest that lesions to the peripheral vestibular system result in impairment of the hippocampus. Nonetheless, relatively few studies have examined the hippocampus or behavior related to it, over a long period of time following the lesion, to determine if any recovery takes place. Here we used the spatial forced alternation task in a T maze, which is sensitive to the integrity of the hippocampus, to evaluate learning and memory in rats at 3 weeks, 3 months, and 5 months following bilateral vestibular deafferentation (BVD) or sham surgery. BVD rats made significantly fewer correct choices at all time points when compared with the sham controls. However, the percentage correct choice for BVD rats was at chance level at 3 weeks postop, and was significantly above chance at 5 months postop. These results add to the evidence that BVD causes a long-term impairment of hippocampal function and spatial learning and memory, but suggest that some recovery of function might take place over the long term.