The mode of breathing affects awareness-related brain potentials: Oral breathing shapes awareness-related brain potentials differently than nasal breathing

Cyclic variation in bodily signals can influence the conscious perception of sensory stimuli. We have previously shown that the respiratory phase affects the sensory processing of visual stimuli during nasal breathing: the P1 component was modulated by awareness only during inhalation. Breathing can affect brain activity both directly through the entrainment of rhythmic brain activity via mechanical stimulation of the olfactory bulb (OB) and indirectly through fluctuations in baroreceptor (BR) activity across the respiratory cycle. We here aim to differentiate the relative contribution of OB stimulation and BR activity by during oral breathing when the OB is not stimulated and show that the early correlates of awareness do not vary with the respiratory phase but vary with the cardiac phase, albeit with somewhat delayed timing. Furthermore, the P3a component was modulated by awareness only when BR activity was low (inhalation, diastole). Our findings clarify the interplay between OB stimulation and BR activity for the conscious processing of a visual stimulus: the fluctuations in BR activity alone cannot explain how early sensory processes affect the perceptual outcome. Only when both OB stimulation is present and BR activity is low, is the P1 the earliest ERP component modulated by awareness.