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Cocco, Giulia

University of British Columbia

Background Adverse childhood experiences affect a significant portion of the global population. Children who endure traumatic events often develop maladaptive cognitive behaviours that can seriously impact their well-being. Notably, these events frequently coincide with infantile amnesia, a developmental period during which crucial memory consolidation structures, such as the hippocampus, are still maturing. This overlap raises an intriguing question: how can a “forgotten” memory continue to shape behaviour? To investigate this, we utilized a mouse model to explore the effects of early life stress (ELS). Methods We used C57BL/6 mice to investigate how fear conditioning (FC) and/or ELS influence behaviour during infantile amnesia. In our protocol, the mice underwent contextual fear conditioning at postnatal day (P) 17 or P30, receiving 15 shocks over 30 minutes while exposed to a tone and an odour. Control mice were placed in the same chambers but received no shocks. Memory recall was assessed one day later and again 30 to 40 days after the conditioning. For our ELS paradigm, we implemented a “scarcity bedding” model, where mice were housed in cages containing only 100 ml of bedding for either 7 days (P3–P10) or 13 days (P3–P16). To evaluate anxiety-like behaviour, we used tests including the open field, elevated plus maze, light/dark box, novelty-suppressed feeding, and social interaction tests. Results We found that mice displayed short-term, but not long-term, recall of the fear event when conditioning took place at P17, indicating that infantile amnesia was active. However, a shift in behaviour did not emerge until scarcity of bedding was introduced. Under these combined stressors, mice showed more “risky” behaviours—rather than typical anxiety—during the elevated plus maze and social interaction tests. Additionally, males appeared more susceptible to these effects. Conclusion Our findings indicate that anxiety-like behaviours may lie on a spectrum and that combining chronic and acute stress can reveal less recognized phenotypes, such as risk-taking behaviour. These results highlight the complexity of how ELS influences adult behaviour and underscore the need to examine the diverse ways stress can manifest later in life.

Text

2025-04-28

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90874

Neuroscience

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/