The effect of threat intensity on episodic conditioned fear memory

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

lingwei ouyang¹ (lingwei.ouyang@utexas.edu), Joseph Dunsmoor¹; ¹University of Texas at Austin

According to associative learning models and animal research, unconditioned stimulus intensity governs facets of Pavlovian fear conditioning (Helfman 1989); including rates of acquisition (Annau & Kamin, 1961), extinction (Storms et al., 1962) and fear memory retention (Codero, Merino & Sandi, 1998). Here, we examined whether US intensity affects episodic memory of fear conditioned stimuli (CS). Fear conditioning can enhance episodic memory selectively for semantic exemplars used as CSs, including for CSs seen before fear conditioning (retroactive enhancement). During conditioning, images from only one category were paired with shock (CS+), while the other category was unpaired with shock (CS-). Notably, as the ceiling on intensity is ethically constrained, we incorporated a highly aversive multimodal US, composed of a high intensity shock and a loud burst of white-noise, and compared episodic memory results to a group receiving a low intensity US. Subjects returned ~24 hours later for a surprise recognition memory task. While low intensity group showed selective retroactive enhancement for neutral items that replicated prior findings (Dunsmoor et al., 2015; Hennings et al., 2021), a high intensity US impaired memory recognition for stimuli in all three experimental phases. This result suggests while higher intensity expedites fear learning in animal models, it may impair episodic memory performance. This has implications for translational research, as the shock intensity commonly used in human research studies may not approximate the deleterious effect on separate implicit and explicit memory systems involved in processing highly aversive events.

Topic Area: LONG-TERM MEMORY: Episodic