title: The effects of voluntary control of respiration on the excitability of the primary motor hand area, evaluated by end-tidal CO2 monitoring.
abstract: OBJECTIVE
  To investigate the effects of voluntary deep breathing on the excitability of the hand area in the primary motor cortex (M1).
  
  
  METHODS
  We applied near-threshold transcranial magnetic stimulation (TMS) over M1 during the early phase of inspiration or expiration in both normal automatic and voluntary deep, but not "forced", breathing in eight healthy participants at rest. We monitored exhaled CO2 levels continuously, and recorded motor-evoked potentials (MEPs) simultaneously from the abductor pollicis brevis, first dorsal interosseous, abductor digiti minimi, flexor digitorum superficialis, and extensor incidis muscles.
  
  
  RESULTS
  We observed that, during voluntary deep breathing, MEP amplitude increased by up to 50% for all recorded muscles and the latency of MEPs decreased by approximately 1ms, compared with normal automatic breathing. We found no difference in the amplitude or latency of MEPs between inspiratory and expiratory phases in either normal automatic or voluntary deep breathing.
  
  
  CONCLUSIONS
  Voluntary deep breathing at rest facilitates MEPs following TMS over the hand area of M1, and MEP enhancement occurs throughout the full respiratory cycle.
  
  
  CONCLUSIONS
  The M1 hand region is continuously driven by top-down neural signals over the entire respiratory cycle of voluntary deep breathing.
authors.affiliation: Department of Physical Therapy, Faculty of Health Sciences, Aomori University of Health and Welfare, 58-1 Mase, Hamadate, Aomori 030-8505, Japan. Electronic address: isamu@auhw.ac.jp.
authors.forename: Isamu
authors.initials: I
authors.lastname: Ozaki
authors.affiliation: Department of Physiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kurata
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation / Q000502:physiology*; D006801:Humans; D001239:Inhalation / Q000502:physiology; D008297:Male; D008475:Median Nerve / Q000502:physiology; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D012119:Respiration; D012132:Respiratory Muscles / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation
chemical_list: D002245:Carbon Dioxide
keywords: Automatic breathing; Hand muscles; Motor-evoked potential; Primary motor cortex; Transcranial magnetic stimulation; Voluntary breathing