title: Pain modulation induced by respiration: phase and frequency effects.
abstract: The voluntary control of respiration is used as a common means to regulate pain and emotions and is fundamental to various relaxation and meditation techniques. The aim of the present study was to examine how breathing frequency and phase affect pain perception, spinal nociceptive activity (RIII-reflex) and brain activity (scalp somatosensory-evoked potentials - SEP's). In 20 healthy volunteers, painful electric shocks individually adjusted to 120% of the RIII-reflex threshold were delivered to the sural nerve near the end of inspiration or expiration phases, during three cued-breathing conditions: (1) slow breathing (0.1 Hz) with slow (4s) inspiration (0.1Hz-SlowIns), (2) slow breathing (0.1 Hz) with fast (2s) inspiration (0.1 Hz-FastIns), and (3) normal breathing (0.2 Hz) with fast (2s) inspiration (0.2 Hz). Pain ratings were not affected by breathing patterns (p=0.3), but were significantly lower during inspiration compared with expiration (p=0.02). This phase effect was also observed on the N100 component of SEP's, but only in the 0.1-Hz-FastIns condition (p=0.03). In contrast, RIII-reflex amplitude was greater during inspiration compared with expiration (p=0.02). It was also decreased in the 0.1-Hz-SlowIns compared with the 0.2-Hz condition (p=0.01). Slow breathing also increased the amplitude of respiratory sinus arrhythmia (RSA), although these changes were not significantly associated with changes in pain responses. In conclusion, this study shows that pain and pain-related brain activity may be reduced during inspiration but these changes are dissociated from spinal nociceptive transmission. The small amplitude of these effects suggests that factors other than respiration contribute to the analgesic effects of relaxation and meditation techniques.
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Université de Montréal, Montréal, QC, Canada H3C 3J7; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Université de Montréal, Montréal, QC, Canada H3W 1W5.
authors.forename: Marianne
authors.initials: M
authors.lastname: Arsenault
authors.forename: Alexandra
authors.initials: A
authors.lastname: Ladouceur
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lehmann
authors.forename: Pierre
authors.initials: P
authors.lastname: Rainville
authors.forename: Mathieu
authors.initials: M
authors.lastname: Piché
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D058748:Pain Perception / Q000502:physiology*; D012063:Relaxation / Q000502:physiology*; D012119:Respiration; D055815:Young Adult
keywords: EMG; EOG; HF; LF; NTS; PCS; RIII-reflex; RSA; SEPs; STAI; State-Trait Anxiety Inventory; analgesia; autonomic; breathing; electroculographic activity; electromyography; high frequency; low frequency; nociceptive flexion reflex; nucleus of the solitary tract; pain; pain-catastrophizing scale; respiratory sinus arrhythmia; somatosensory-evoked-potentials