The aperiodic exponent of resting-state pupil fluctuations predicts excitation/inhibition balance in attentional processing

Abstract

The aperiodic exponent features neural signals in various modalities and has been linked to the excitation/inhibition balance of the neural system. Leveraging the rich temporal dynamics in the resting-state pupil fluctuations, the present study took the first attempt to investigate the cognitive significance of the aperiodic exponent of pupil fluctuations and its association with the neural excitation/inhibition balance in attentional processing. In separate phases, we recorded participants' pupil fluctuations during the resting state and evaluated their visual attention using the Posner cueing task with varied cue validity (i.e., 100% and 50%). We found significant correlations between the aperiodic exponent of resting pupil fluctuations and both the microsaccadic and behavioral responses indicative of attentional processing characteristics. Critically, this association was particularly evident under the condition of high stimulus uncertainty (i.e., with 50% cue validity), highlighting the strong reliance on neural excitation/inhibition balance. Further analysis revealed that the aperiodic exponent of pupil fluctuations predicted the severity of ADHD symptoms of hyperactivity/impulsivity across individuals, suggesting its potential as a marker for attentional deficiency traits. These findings underscore the rich information contained in pupil fluctuations and provide a novel approach to evaluating the neural excitation/inhibition balance in cognitive processing, both in normal and abnormal attention.