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Poster F in Poster Session F: Thursday, August 6, 1:45 – 3:30 pm, Kimmel Center, Shorin & Rosenthal Rooms

Stable endogenous brain–body dynamics dominate cortical activity during naturalistic cognition

Jens Madsen¹, Behtash Babadi², Aimar Silvan¹, Lucas Parra¹; ¹CUNY City College of NY, ²University of Maryland, College Park

Presenter: Jens Madsen

Understanding how the brain processes naturalistic stimuli requires disentangling stimulus-driven responses from ongoing endogenous activity. Slow neural and physiological fluctuations are ubiquitous, yet it remains unclear whether cognition reorganizes these interactions or operates within a stable dynamical system. We recorded EEG, pupil size, heart rate, respiration, electrodermal activity, and eye movements from 66 participants during narrative listening and rest. Using a vector autoregressive model with exogenous inputs (VARX), we separated intrinsic brain–body dynamics from stimulus-driven effects. Brain-body interactions were dominated by a stable endogenous system that was largely unchanged across conditions. Peripheral physiology and behavior exerted stronger influences on cortical activity than the reverse, indicating dominant bottom-up contributions. In contrast, external stimulus features explained only a small fraction of EEG variance. These results suggest that cortical activity during naturalistic cognition is governed primarily by intrinsic brain-body dynamics, with external inputs coupling weakly into this system.

Topic Area: Methods, Tools, Theory & Neural Coding