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.

We developed a method to detect and superimpose neuronal populations involved in two different episodes of activity in the brain of single animal. This method is based on usage of two transcriptional factors with different accumulation curves, c-Fos and pCREB, as the markers. The overlap of neuronal populations involved in performance of spatial and nonspatial tasks in Morris water maze has been shown to occur at "chance" level.