Modulatory dynamics of periodic and aperiodic activity in respiration-brain coupling

Bodily rhythms such as respiration are increasingly acknowledged to modulate neural oscillations underlying human action, perception, and cognition. Conversely, the link between respiration and aperiodic brain activity – a non-oscillatory reflection of excitation-inhibition (E:I) balance – has remained unstudied. Aiming to disentangle potential respiration-related dynamics of periodic and aperiodic activity, we applied novel algorithms of time-resolved parameter estimation to resting-state M/EEG data from two recording sites (N = 78). Our findings highlight the role of respiration as a physiological influence on brain signalling. We provide first evidence that fluctuations of aperiodic brain activity (1/f slope) are phase- locked to the respiratory cycle which strongly suggests that spontaneous state shifts of excitation-inhibition balance are at least partly influenced by peripheral bodily signals. Moreover, differential temporal dynamics in their coupling to non-oscillatory and oscillatory activity point towards a functional distinction in the way each component is related to respiration.