Lack of hippocampal involvement in a rat model of petit mal epilepsy.

Although petit mal epilepsy is believed to arise from the thalamocortical system, it has been suggested recently that high-voltage spike-and-wave activity (HVS) in mutant mice can cause structural reorganization in the hippocampus, similar to that seen in temporal lobe epilepsy. We tested this assumption in rat strains with low and high incidence of HVS. No relationship was found between mossy fiber sprouting and HVS incidence. Hippocampal neurons were not driven by HVS. These findings suggest that petit mal seizures do not invade the hippocampus and are not causally related to sprouting of the mossy fibers.