Before revision:  In this study, we investigated whether simultaneous multimodal EEG-fMRI combined with eye-tracker measurements can be used to determine EEG signal feature associated with pupil sizechanges (e. g., vigilance measure) in healthy human subjects (n= 10 ) during brain rest with eyes open. We found that EEG frontal and occipital beta power (FOBP) correlates with pupil size changes, an indirect index for locus coeruleus activity implicated in vigilance regulation (r = 0.306, p < 0.001).
After revision:  In this study, we investigated whether simultaneous multimodal EEG-fMRI combined with eye-tracker measurements can be used to determine EEG signal feature associated with pupil sizechanges (e. g., vigilance measure) in healthy human subjects (n= 10 healthy control participants. We simultaneously collected EEG, fMRI, physiological, and eye-tracker data and investigated the correlation between EEG features, pupil size, and heart rate. Furthermore, we used pupil size and EEG features as regressors to find their correlations with blood-oxygen-level-dependent fMRI measures. Results: EEG frontal and occipital beta power (FOBP) correlates with pupil size changes, an indirect index for locus coeruleus activity implicated in vigilance regulation (r = 0.306, p < 0.001).