Hippocampal kindled seizures impair spatial cognition in the Morris water maze

We investigated the effects of hippocampally kindled seizures on spatial performance of rats in the Morris water maze (MWM). Seizures were elicited with stimulation of field CA1 of dorsal hippocampus 25-45 min prior to daily testing in the water maze. One group of rats was naive to the MWM (acquisition groups), while another group received pretraining in the MWM (retention groups). These groups were further subdivided into rats that experienced non-convulsive seizures prior to daily testing and rats that experienced fully generalized convulsive seizures prior to daily testing. We found that CA1 seizures significantly disrupted water maze performance during both acquisition and retention, and the effects were similar when either non-convulsive or fully generalized convulsive seizures were evoked. Our findings are consistent with previous reports suggesting that epileptiform activity in the hippocampus acutely impairs performance in tasks sensitive to spatial learning and memory deficits and suggest that both new learning and demonstration of an established place response are susceptible to such disruption.