Impact of Breathing Phases on Social Stimuli Processing

Abstract

Recent studies have demonstrated the respiratory entrainment of brain cycles, leading to implications for cognitive and emotional processes. Notably, the preBötzinger complex, an important breathing area, sends out inhalation-modulated projections to the locus coeruleus, amygdala, and hippocampus, essential for arousal, emotion, and memory. Using a breathing phase-locked face processing task (with neutral face pictures), this study investigated breathing phases’ effect on emotion and memory processing at behavioral and neural levels, using negativity ratings, memory performance, and ERP (event-related-potential) measures of early (N170) and later (P300) processing. Participants provided negativity ratings to faces that were presented either at the inhalation or exhalation phase of breathing cycles, while their neural activity was being recorded using EEG (electroencephalograph). Their memory for the faces was later tested and their trait anxiety and depression were measured using questionnaires. It was hypothesized that the negativity ratings, memory accuracy, N170 and P300 amplitude will be greater for inhalation versus exhalation phases. Results indicated no differences in negativity ratings and overall face recognition memory between the two breathing phase conditions. However, we found evidence that recognition memory was enhanced for faces encoded at inhalation and retrieved at exhalation. Accuracy of correct rejection was enhanced during the inhalation versus exhalation phase. There were no breathing phase differences between a priori selected electrodes P9/P10 for ERP N170 and Pz/POz for P300. However, N170 at other electrodes in the parietal regions showed a greater negative amplitude for the inhalation versus exhalation phase. A significant correlation was found between high levels of depression and negativity rating differences between the phases. Taken together, our results support the idea that the limbic system, and related cognitive/affective processes, can be modulated by different phases of breathing cycles, which justifies further mechanistic investigations on how breathing rhythms and techniques affect human emotion and cognition.