Influence of contextual exposure on memory strength and precision for inhibitory avoidance in male and female rats

Aversive associative learning paradigms such as inhibitory avoidance (IA) are frequently used to examine episodic-like memories in rodents. In IA, rodents learn to associate a context with a footshock, with testing for memory strength in the original training context and memory precision in a similar yet distinct neutral context. The present work assessed how different contextual exposure procedures affect memory strength and precision in IA at both recent and remote time points using male and female Long-Evans rats. An initial experiment found that rats kept in the lit (non-shock) compartment of the IA apparatus for 60 sec during training, as opposed to 10 sec, displayed enhanced memory strength, with discrimination between both chambers at the recent retention test and generalization at the remote retention test. Subsequent experiments investigated the effects of contextual pre-exposure the day before training. The results indicate that pre-exposure to the neutral context promoted generalization without altering memory strength compared to the first experiment, whereas pre-exposure to the aversive chamber promoted discrimination and memory strength. Notably, the different procedures yielded similar effects in both sexes. However, the results also indicate an overall pattern of greater contextual discrimination in females compared to males. These findings provide evidence for how different contextual exposures influence the degree of encoding at the time of training and a behavioral foundation for future studies examining the neurobiological mechanisms underlying memory strength and precision in IA, while highlighting the importance of using both sexes in initial behavioral work.