Neural activity is modulated by spontaneous and volitionally controlled breathing.

Recent studies have provided evidence regarding respiration-brain coupling, but our understanding of how continuously varying dynamics of breathing modulate neural activity remains incomplete. We examined whether the neural state differs between spontaneous and volitionally controlled breathing and across the phases of breathing, inspiration and expiration. Magnetoencephalography (MEG) with a respiratory belt was used to record cortical oscillatory activity during spontaneous, deep, and square breathing (n = 33). Additionally, self-report measures of mood and arousal were applied to assess changes in the psychological state during the breathing techniques. Alpha power was suppressed during inspiration and increased during expiration (p < .01) indicating dynamically fluctuating neural states across the respiratory cycle. This effect was observed in the sensorimotor areas during both spontaneous and volitionally controlled deep breathing. Compared to spontaneous and volitionally controlled square breathing, alpha power increased during deep breathing (p < .01) within a cortical network extending to frontal and temporal areas. We also observed a steeper aperiodic slope and a broadband shift in the power spectrum in the left superior frontal gyrus during square breathing in comparison with spontaneous breathing suggesting that not only oscillatory activity but also the more general spectral characteristics of ongoing neural activity are modulated by the rate, depth, and pattern of breathing. Self-reported mood and arousal did not differ across the breathing techniques. Altogether, we demonstrate that neural activity is modulated by the phases of breathing and can also be volitionally influenced by varying the rate, depth, and pattern of breathing.