Impact of Drowsiness on EEG-fMRI Dynamics and Physiological Responses During Eyes-Open and Short Resting State Scans

Motivation: Drowsiness impacts brain function and physiology, affecting the interpretation of resting-state fMRI scans. Understanding its dynamics is crucial for accurate analysis. Goal(s): Investigate how EEG-defined drowsiness, marked by alpha-power changes, modulates brain connectivity and physiological responses(heart-rate, pulse amplitude, respiratory variability) during resting-state fMRI. Approach: Participants were grouped based on alpha power shifts. EEG-fMRI data were correlated with heart rate, pulse amplitude, and respiratory variability. Results: In drowsy state, HR showed stronger correlations with the ACC and visual cortex, indicating greater synchrony between brain and heart. PPG-AMP coupled more with sensory regions, and RV linked to DMN areas, with reduced connectivity in drowsy group. Impact: This study provides new insights into the effects of drowsiness on brain-physiological interactions, which could improve the interpretation of resting-state fMRI scans in both research and clinical settings.