Poster E89, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
How does the timing of acute stress modulate hippocampal connectivity following associative encoding?
Alexa Tompary1, Elizabeth V. Goldfarb1, Elizabeth A. Phelps1, Lila Davachi1; 1New York University
Acute stress is known to influence episodic memory, and the directionality of this influence depends on the stage of memory formation during which the stressor is administered. Most prior work focuses on the influence of stress on recognition memory, leaving open the question of how hippocampus-based associative memory is affected by stress. We developed a two-day fMRI study with a fully within-subject design to investigate how neural processes during post-encoding rest are influenced by stressors that occur either before or after encoding, and how these processes relate to long-term memory. In the first session, participants completed a baseline rest scan, and then encoded neutral objects paired with previously normed negatively valenced words. The cold pressor stress manipulation was administered immediately after the second encoding block, resulting in three encoding conditions: no stress, post-encoding stress, and pre-encoding stress. These scans were interleaved with three post-encoding rest scans. 24 hours later, participants completed recognition and source memory tests. We investigated shifts in resting state connectivity between the hippocampus and object-sensitive regions in ventral temporal cortex. We found that following encoding with no stress, connectivity between the hippocampus and object regions increased relative to baseline, consistent with past work (Tambini et al., 2010). However, if stress occurred before encoding, hippocampal connectivity during post-encoding rest was significantly lower. This suggests that stress administered before encoding may disrupt consolidation processes that begin to unfold immediately after encoding. Further analyses will connect these imaging findings to individual differences in recognition and source memory across participants.
Topic Area: LONG-TERM MEMORY: Episodic