Emotion and respiration

Abstract

It is well known that respiratory rhythm and pattern are generated in the respiratory centre located in the lower brainstem. This is the centre for autonomic metabolic control system. However, respiratory patterns during awake state are affected by various inner or outer environmental changes. This system is called the behavioural respiratory system. Within the system, there is an emotional breathing, which is altered by emotional changes. We used two experimental techniques, which have been developed in our laboratory, for establishing physiological characteristics in emotional breathing. Subjects’ EEG, airflow and end-tidal CO2 were monitored. Before the test, the subjects’ anxiety was assessed by Spielberger’s State Trait Anxiety Inventory. Breathing pattern is altered by various mental states including anxiety. The respiratory rate increased and end-tidal CO2 decreased during anticipatory anxiety. The increase in respiratory frequency was higher in the subjects with high trait anxiety than in the subjects with low trait anxiety. Differences in respiratory frequency before and during anticipatory anxiety and Trait anxiety scores had a positive correlation (P < 0.05). We recorded Respiratory-related Anxiety Potential in EEG recordings during anticipatory anxiety. Respiratory-related Anxiety Potential was observed 300–400 ms after the onset of inspiration. During this period, dipole location was estimated by the dipole tracing method (BS-navi, BRAD NY and Tokyo). The source was located in the temporal pole and amygdala.1,2 Olfactory perception is related to emotion and is dependent on inspiration. We examined respiration and EEG simultaneously during pleasant or unpleasant odour stimulation. The respiratory rate increased when the subjects inhaled unpleasant odour. Alpha waves were locked on inspiration during odour stimulation. During this inspiration phase-locked alpha waves (I-α) dipoles were estimated in the limbic area: the entorhinal cortex, hippocampus, amygdala and orbitofrontal cortex.3 The limbic-spinal cord preparations of 0- to 1-day-old rats were isolated under deep anaesthesia. The preparation was transected rostrally to visualize the amygdala and piriform cortex on the surface of rostral cut end. Neural activities were detected as changes in fluorescence of the voltage-sensitive dye by means of optical recording apparatus. Spontaneous rhythmic activities were observed in the piriform cortex around the onset of inspiration and the activities propagated to the amygdala. These respiratory rhythmic activities may relate to olfaction and olfaction related emotional changes.4 Amygdala may be the centre that produces breathing rhythm for the emotional breathing.