Theta EEG activity and memory processes in rats

Rodent EEG theta activity recorded in the 30 min period after ECS treatment has previously been correlated with passive avoidance retention. In the present experiment rats were trained and tested in an appetitive maze, thereby avoiding the possible confounding of footshock-produced EEG arousal. Our results produced the same relationship between theta and retention, but since ECS was given 7 days after training, we conclude that theta activity is not related only to memory consolidation. Patterns of theta during reinstatement were also found to be more similar to the pattern recorded late in learning when the reinstatment took place in the original start box. The data support the notion of cue-dependent amnesia, and the hypothesis that ECS acts by inhibiting the memory which is active at the time of ECS.