Differential Retrieval of Contextual Fear-Conditioned Memory in Adolescent and Adult Rats.

Abstract

Memory retrieval is an important memory process, and its effectiveness can vary across developmental stages. The differential maturation of hippocampal- and non-hippocampal-dependent memory systems suggests that distinct forms of memory develop along separate neurodevelopmental time points. However, it is unclear if hippocampal-dependent fear memory retrieval differs between adolescence and adulthood. We hypothesize that developmental changes in brain function contribute to differences in memory retrieval between adolescent and adult animals. Accordingly, this study examines age-dependent differences in the retrieval of contextual fear-conditioned memory by comparing adolescent and adult rats. The experiment involved three different cohorts of rats (N=32). Group A comprised adolescent rats (N=12) trained at postnatal day 30 (P30) and tested 10 days later at P40. Group B consisted of adult rats (N=10) trained at P80 and tested 24hours later at P81, while Group C included adult rats (N=10) trained at P80 but tested 10 days later at P90. Results indicated that adolescent rats had a more substantial capacity to recall contextual fear memories than adult rats. While adult rats showed a significant increase in freezing behavior 24hours after training, adolescent rats exhibited greater freezing behavior when tested 10 days post-training, highlighting the developmental changes in fear and anxiety processing associated with the maturation of the hippocampus and amygdala.