Recovery of impaired memory and c-fos gene expression in brains of amnestic animals in response to reminder stimulation.

Possible mechanisms of recovery of the memory impaired during consolidation process were investigated. In mice, amnesia was induced by intraperitoneal cycloheximide (100 mg/kg) administration 20 min before exposure to tone signal combined with footshock (2 sec, 0.5 mA). Reminder by the footshock (2 sec, 0.5 mA) 24 h after the learning procedure resulted in recovery of impaired memory in amnestic animals up to the level of control animals. Analysis of c-Fos expression in response to reminder indicated increased number of c-Fos-positive cells in prelimbic cortex in the animals with unaffected memory in comparison with corresponding parameter in amnestic animals. These findings are indicative of impairment in prelimbic cortex activity in experimental amnesia as well as for reminder ability to recover the memory impaired in that way.