CUE FAMILIARITY REDUCES SPATIAL DISORIENTATION FOLLOWING HIPPOCAMPAL DAMAGE

The purpose of this study was to determine whether familiarity with a cue would enhance the ability of rats with hippocampus (HPG) damage to locate a cued bidden platform in the Morris water test. After preoper ative training with the cue (n = 21) or handling only (n = 17), rats w ere given electrolytic bilateral HPC lesions or sham surgery for contr ols. All rats were then tested for 4 days, 6 trials per day, with the cue marking the platform location. Rats with HPC lesions familiar with the cue (FB) were significantly more efficient than rats with HPC les ions unfamiliar with the cue (UB) in swim time (M = 10.31 +/- 2.2 vs 4 6.72 +/- 7.5 sec, p < .05) and in directional beading error (M = 31.98 +/- 3.4 vs 57.92 +/- 4.0 degrees, p < .05) on Day 1. These difference s occurred across the 4 test days and were shown to be the result of a n impairment in learning of the cue task in the UB groups rather than simply an effect of more practice with the cue by FB animals. No signi ficant differences were found between FB animals and familiar controls .