THE GENETICALLY EPILEPSY-PRONE RAT (GEPR)

Two independently inbred strains of genetically epilepsy-prone rats (G EPRs) have been developed. GEPR-3s and GEPR-9s have moderate and sever e degrees of seizure predisposition as well as expression, respectivel y. Seizure predisposition is a fundamental distinction between the nor mal and epileptic brain. Seizure predisposition in GEPRs and in humans with epilepsy includes spontaneous seizures and exaggerated seizure r esponsiveness and/or abnormally low thresholds to stimuli which also c ause seizures in non-epileptic subjects. Activation of brainstem seizu re circuitry by auditory input via the inferior colliculus causes elec trographic and behavioral responses in GEPR-9s which replicates human generalized tonic/clonic seizures, Activation of brainstem seizure cir cuitry by input from forebrain seizure circuitry in GEPRs provides a n ewly discovered model of complex partial seizures with secondary gener alization to tonic/clonic seizures, Thus seizure predisposition in GEP Rs offers a unique opportunity to study the human epilepsies that is n ot offered in studies of normal brain exposed to convulsant stimuli.