Schedule of Events | Symposia

Modulating declarative memory with direct human amygdala stimulation

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

Martina Hollearn¹ (martina.hollearn@psych.utah.edu), Joseph Manns², Lou Blanpain², Stephan Hamann², Kelly Bijanki³, Robert Gross², Daniel Drane², Krista Wahlstrom¹, Justin Campbell¹, Griffin Light¹, Aydin Tasevac¹, Zack Wilson¹, Jon Willie⁴, Cory Inman¹; ¹University of Utah, SLC, UT, ²Emory University, Atlanta, GA, ³Baylor College of Medicine, Houston, TX, ⁴Washington University, St. Louis, St. Louis, MI

We previously demonstrated that brief electrical stimulation to the basolateral amygdala (BLA) enhances declarative memory in humans after a one-day delay without triggering an emotional response. Retrieval-based neural signals, like increased gamma (~50 Hz) power in the perirhinal cortex, have been observed as an “echo” of prior BLA stimulation for remembered objects. This study builds on those findings by increasing the sample size and examining retrieval-based neural signals across medial temporal lobe (MTL) regions. We recruited 31 drug-resistant epilepsy patients undergoing stereotactic EEG surgery, with depth electrodes implanted in various MTL regions. Participants were presented with images of neutral objects during continuous intracranial EEG recording. Brief BLA stimulation (8 trains of 50-Hz pulses at 0.5 mA) was delivered before, during, or after image presentation, with varying durations to optimize memory enhancement. Stimulated objects were recognized more accurately at the one-day delay compared to non-stimulated objects (t(30) = 2.90, p = .007, d = .44). A comprehensive linear mixed effects model revealed theta and gamma power increases in MTL regions (e.g., hippocampus, BLA, entorhinal, perirhinal, and parahippocampal cortices) for remembered objects. Furthermore, the relationship between BLA stimulation and memory enhancement was non-linearly influenced by baseline long-term memory capacity. These findings indicate that brief BLA stimulation can enhance item-specific memory for neutral objects without awareness, highlighting the amygdala's critical role in prioritizing experiences for long-term storage. Future research in humans and animals is necessary to optimize amygdala-mediated memory enhancement strategies.

Topic Area: LONG-TERM MEMORY: Episodic