title: Activation of the prefrontal cortex is associated with exertional dyspnea in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Exertional dyspnea is the primary symptom that limits exercise in patients with chronic obstructive pulmonary disease (COPD). It is unknown which activated brain area is associated with this symptom in COPD patients.
  
  
  OBJECTIVE
  To investigate the activation of cortical areas associated with dyspnea during exercise in COPD patients.
  
  
  METHODS
  COPD patients (n = 10) and age-matched controls (n = 10) performed mild-intensity constant work rate cycle exercise (40% of their symptom-limited peak work rates) for 10 min, while cerebral hemodynamics and oxygenation were measured by near-infrared spectroscopy (NIRS). Ventilatory responses (breathing pattern and pulmonary gas exchange) and Borg scale ratings of dyspnea and leg fatigue were measured during exercise. Three NIRS probes were placed over the prefrontal and temporoparietal cortical regions of the subjects' heads. Changes in cortical oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), and total hemoglobin (total Hb) concentrations from baseline recordings were measured. Increased oxy-Hb (oxygenation) was assumed to reflect cortical activation.
  
  
  RESULTS
  Oxy-Hb concentration was significantly increased in the prefrontal region during exercise in both groups but not in the temporoparietal regions. The change in prefrontal oxy-Hb concentration of COPD patients was not different from that of controls. Dyspnea scores were positively correlated with changes in oxy-Hb concentrations of the prefrontal regions in both groups. Multivariate analysis showed that oxy-Hb concentration in the prefrontal region was the best predictor of dyspnea in both groups.
  
  
  CONCLUSIONS
  Exertional dyspnea was related to activation (oxygenation) of the prefrontal cortex in COPD patients and control subjects.
authors.affiliation: Department of Rehabilitation Medicine, Kinki University, Faculty of Medicine, Osaka, Japan. yhigashi@med.kindai.ac.jp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Higashimoto
authors.forename: Noritsugu
authors.initials: N
authors.lastname: Honda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamagata
authors.forename: Toshiki
authors.initials: T
authors.lastname: Matsuoka
authors.forename: Kazushige
authors.initials: K
authors.lastname: Maeda
authors.forename: Rhyuji
authors.initials: R
authors.lastname: Satoh
authors.forename: Osamu
authors.initials: O
authors.lastname: Nishiyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sano
authors.forename: Takashi
authors.initials: T
authors.lastname: Iwanaga
authors.forename: Takayuki
authors.initials: T
authors.lastname: Miyara
authors.forename: Masato
authors.initials: M
authors.lastname: Muraki
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Tomita
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kume
authors.forename: Ichiro
authors.initials: I
authors.lastname: Miyai
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tohda
authors.forename: Kanji
authors.initials: K
authors.lastname: Fukuda
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D004417:Dyspnea / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D010108:Oxyhemoglobins / Q000378:metabolism; D011237:Predictive Value of Tests; D017397:Prefrontal Cortex / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012016:Reference Values; D019265:Spectroscopy, Near-Infrared
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin