Schedule of Events | Symposia

event boundary modulation of theta-oscillations in the hippocampus and amygdala

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

Brandon Katerman¹ (katerman@ucla.edu), David Clewett²; ¹UCLA

Event boundaries play a critical role in structuring continuous experiences into discrete, memorable episodes. Recent work using short neutral video clips has shown that activity in medial temporal lobe structures (MTL) are responsive to boundaries on the timescale of milliseconds, suggesting that they may play an important role in signaling important changes and promoting the separation of adjacent memories. However, this effect was only examined using single-unit recordings and with a series of short, unrelated video clips. Using intracranial electroencephalography (iEEG) recordings from the hippocampus and amygdala, we investigated spectral power changes associated with event boundaries during an emotionally engaging 43-minute viewing of a TV episode. A separate group of participants provided real-time emotion ratings while watching the episodic, enabling us to assess the level of arousal and valence in each scene, or event. Analyses were focused on theta (3 – 8Hz) and gamma (50-180Hz) frequency bands, which have been associated with memory-related encoding and retrieval processes in controlled word list and object recognition paradigms. Time-averaged analyses revealed significant increases in theta (3-8 Hz) power at scene-change boundaries within the anterior hippocampus and amygdala compared to matched within-event time points. We also found that event boundaries that followed high- versus low-arousal events led to greater theta suppression in both of these brain regions. These findings help to advance our understanding of how temporally dynamic activity in MTL structures are modulated by meaningful changes in naturalistic contexts, including shifts in emotional arousal.

Topic Area: LONG-TERM MEMORY: Episodic