Abstracts

RATIONALE: Seizures during early development are associated with impaired learning in the water maze when animals are tested as adults. The physiological basis for this impairment is not known. Here we report the use of single unit recordings from place cells in the CA1 and/or CA3 regions of the hippocampus in rats following status epilepticus. METHODS: Two groups of rats were used: rats undergoing to status epilepticus at postnatal day (P)20 using lithium-pilocarpine (n=6) and saline controls (n=6). When studied as adults (P60), these animals have impaired learning in the water maze. Multiple channel electrodes were implanted into the CA1 and/or CA3 regions of the hippocampus and place cells recorded. RESULTS: Place cells, cells which have action potentials only when animals are in a specific location, were recorded in both controls and animals subjected to status epilepticus. Morphology of the single unit potentials were similar in both groups, although the spatial specificity and reproducibility of place cell firing maps were impaired in animals with status epileptus compared to controls. CONCLUSIONS: Prolonged seizures during early developement adversely alter place cell physiology. Place cells appear to be a surrogate marker of the integrity of visual-spatial memory.