Synchronized Feeding as a “Conditioned Stimulus” for Overt Seizures in Chronically (Limbic) Epileptic Rats: A Model for “Psychogenic Seizures” with Complex Partial Epilepsy

Abstract

Chronic limbic epilepsy was induced in male albino rats by a single systemic injection of lithium (3mEq/kg) and pilocarpine (30mg/kg). During the subsequent months the numbers of spontaneous, paroxysmal stereotyped episodes (analogous to Racine stages 4 and 5) were monitored. The numbers of these “overt seizures” increased within 10 min of the daily presentation of a food stimulus even though food was available ad libitum. The majority of the paroxysmal, stereotyped behaviours occurred within 1 min of the stimulus presentation; they were attenuated by oral prednisolone. Three rats displayed evidence of “conditioned seizures” to specific stimuli. The results suggest that the display of these behaviours can be synchronized and learned in contexts that are associated with the release of CRF (corticotrophin releasing factor) and may involve the disinhibited activity within the central amygdaloid nucleus of these rats. Implications for the occurrence of psychogenic seizures in patients with complex partial (limbic) epilepsy are discussed.

Key Words:

• Limbic seizure
• Complex partial seizure
• Conditioning lithium
• Pilocarpine
• Rat
• Food synchronization
• Corticotrophin