Schedule of Events | Symposia

Inhibition of the Left Amygdala via Low-Intensity Focused Ultrasound Enhances the Encoding of Emotional and Neutral Episodic Memories

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Sydney Lambert¹ (sydney.lambert@austin.utexas.edu), Manoj Doss¹, Charles Nemeroff¹, Gregory Fonzo¹, Joseph Dunsmoor¹; ¹The University of Texas at Austin

The amygdala is thought to be crucial to the formation and encoding of emotional episodic memories, but causal evidence for this assertion in humans is limited. In a double-blind, sham-controlled, repeated measures study (N = 18), we inhibited the left amygdala with low-intensity focused ultrasound during the encoding of emotional episodic memories. Following sonication, participants completed the encoding phase of an emotional episodic memory task in which emotionally negative, neutral, and positive pictures were presented. The following day, participants completed the retrieval phase in which memory for pictures was tested on a cued recollection test and picture recognition test. Surprisingly, active vs. sham sonication enhanced memory for negative, neutral, and positive stimuli (main effect of sonication on cued recollection memory accuracy: F(1,17) = 4.35, p = .005, ηp2 = .20), without differential effects of sonication on emotional stimuli (sonication × emotion interaction on cued recollection memory accuracy: (F(2, 34) = .86, p > .250). Memory enhancements were found across multiple other measures on both memory tests and came from an increase in hit rates (rather than a decrease in false alarm rates). These findings motivate a novel hypothesis for the role of the amygdala in emotional episodic memory. Rather than the amygdala enhancing memory via amplification of salient stimuli, it may instead act as a filter that attenuates the maintenance of non-salient stimuli in long-term memory. With temporary inhibition, these findings suggest that memory can be acutely enhanced, thereby opening avenues for transient memory enhancements in disorders exhibiting mnemonic impairments.

Topic Area: LONG-TERM MEMORY: Episodic