Experimental animal model of transient global amnesia: Role of the hippocampus

Different groups of rats were given a hippocampal seizure after-discharge 1 or 7 days after acquiring a passive avoidance, active avoidance, or bar-pressing habit. At various delays after the cessation of the seizure after-discharge, the animals were tested for retention of the previously acquired habit. The results indicate that 1 day, but not 7 days after learning, hippocampal seizures are capable of producing a temporary retrograde amnesia for well-learned responses and an anterograde amnesia for experiences that occur during the retrograde amnesia period. These data suggest that hippocampal seizures can serve as an experimental prototype of "transient global amnesia" and that the hippocampus is critically involved in retrieval of information from long term memory.