Caffeine-Induced Reductions in the Resting-State fMRI Global Signal Reflect Increases in EEG Vigilance Measures

Chi Wah Wong¹, Valur Olafsson¹, Omer Tal¹, Thomas Liu¹

A prior study has shown that caffeine reduces the amplitude of the global signal in resting-state fMRI and enhances the anti-correlation between the Default Mode Network (DMN) and Task Positive Network (TPN). In this study, we used simultaneous EEG-fMRI to investigate the neural-electrical basis of these caffeine-related effects. We found that the caffeine-induced changes in the global signal amplitude are negatively correlated with changes in vigilance derived using EEG.