{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T06:05:23Z","timestamp":1782281123786,"version":"3.54.5"},"posted":{"date-parts":[[2026,3,13]]},"group-title":"Neuroscience","reference-count":39,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T00:00:00Z","timestamp":1773360000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/"}],"funder":[{"DOI":"10.13039\/100000025","name":"NIMH","doi-asserted-by":"crossref","award":["MH117426"],"award-info":[{"award-number":["MH117426"]}],"id":[{"id":"10.13039\/100000025","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,3,13]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>Traumatic stress can cause long-lasting changes in cognition and affect, sometimes leading to diagnoses such as post-traumatic stress disorder (PTSD). The stress-enhanced fear learning (SEFL) model recapitulates understudied components of PTSD, such as stress-induced sensitization of fear learning. The SEFL procedure entails exposing mice to footshock stress followed later by fear conditioning in a different context. When tested later for recall of fear conditioning, previously stressed mice exhibit enhanced freezing compared to non-stressed controls. Studies have shown that dorsal and ventral dentate gyrus (DG) generates neural ensemble representations of contextual fear, such that fear recall involves reactivation of a sparse set of \u201cengram cells\u201d that were active during fear memory acquisition. How stress affects these hippocampal ensemble representations is unknown. We used SEFL and activity-dependent neuronal tagging with FosTRAP2 mice to investigate effects of stress on fear memory ensembles in rostral and caudal hippocampal DG. FosTRAP2\/Ai6 mice received footshock stress or equivalent context exposure without shock in Context A on day 1. Five days later, mice received 1-shock conditioning in Context B and immediately received an injection of 4-OHT (55mg\/kg) to tag fear acquisition neurons with the zsGreen reporter. One day later, mice were tested for fear recall in Context B and were perfused 90 minutes after testing. Confirming prior studies, prior stress potentiated 1-shock conditioning in Context B, with stressed mice displaying higher freezing in the Context B test session than non-stressed mice. At the level of neural activity, results showed stress had no effect on the number of zsGreen+ fear ensemble cells or the number of cfos+ recall-activated cells in rostral or caudal DG. However, stress increased reactivation (percentage of zsGreen+ cells expressing cfos) in the caudal but not rostral DG. The results suggest stress potentiates later fear learning by enhancing fear representations in caudal hippocampus, a region of the hippocampus specialized for integrating emotional and motivational valence into memory.<\/jats:p>","DOI":"10.64898\/2026.03.11.710413","type":"posted-content","created":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T08:40:18Z","timestamp":1773391218000},"source":"Crossref","is-referenced-by-count":0,"title":["Stress-Enhanced Fear Learning (SEFL) is Associated with Enhanced Reactivation of Fear Engrams in Caudal but not Rostral Dentate Gyrus"],"prefix":"10.64898","author":[{"given":"Denisse","family":"Paredes","sequence":"first","affiliation":[{"name":"University of Texas in Austin, Austin, TX"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Drew","sequence":"additional","affiliation":[{"name":"University of Texas in Austin, Austin, 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