Pupil-linked phasic arousal relates to the reduction of response inhibition: inferences from a simultaneous pupillometry and EEG-fMRI study

Attention reorienting is a critical cognitive function which drives how we respond to novel and unexpected stimuli. In recent years, arousal has been linked to attention reorienting. The timing and spatial organization of the interactions between the arousal and reorienting systems, however, remain only partially revealed. Here, we investigate the dynamics between the two systems through simultaneous recordings of pupillometry, EEG, and fMRI of healthy human subjects while they performed an auditory target detection task. We used pupil diameter and activity in the noradrenergic locus coeruleus to infer arousal, and found these measures linked to distinct cortical activity at various temporal stages of the reorienting response. Specifically, our results provide the first demonstration in humans of how phasic pupil-linked arousal relates to the reduction of response inhibition, an inference which otherwise would remain hidden without the help of simultaneous multi-modal acquisitions. ### Competing Interest Statement Paul Sajda is a scientific advisor to Optios Inc. and OpenBCI LLC.