Brain function during dyspnea sensation

慢性阻塞性肺疾病（COPD）的早期症状是运动时呼吸困难，严重的COPD即使在安静呼吸时也有呼吸困难。呼吸困难在大脑中被感知。然而，呼吸困难时的脑功能并非未知。本研究的目的是检查呼吸困难时的脑功能。我们通过使用脑成像技术、正电子发射断层扫描（PET）和统计参数图，检查了健康受试者在阻力性吸气负荷呼吸期间和重度COPD患者在安静呼吸期间的脑功能。正常对照组在静息呼吸时注射18（18 F）-氟脱氧葡萄糖（FDG），另一组在施加吸气阻力后注射。重度COPD患者的PET检查仅在静息呼吸时进行，我们观察了以下脑区的激活部位和失活部位：1）正常组呼吸困难随阻力负荷的增加而增加。正常组采用阻力性负荷呼吸。中央前回、中央后回和眶回部位被激活，楔前回、额中回、顶叶上回和扣带回部位被失活。2）重度COPD患者，舌回、颞上级回和眶回部位被激活，楔前回、扣带回、颞叶、扣带回部位被激活。3）正常组和COPD组均激活眶回，楔前叶、扣带回和上级顶叶失活。本研究中观察到的大脑激活和失活的生理意义尚未阐明。

The early symptom of chronic obstructive pulmonary disease (COPD) is dyspnea during exercise, and severe COPD has dyspnea even while quiet breathing. Dyspnea is perceived in the brain. However, brain function during dyspnea has not been unknown. The aim of this study was to examine the brain function during dyspnea. We examined brain function during resistive inspiratory loaded breathing in healthy subjects and during quiet breathing in severe COPD patients, by using a brain imaging technique, positron emission tomography (PET) and statistical parametric mapping. PET studies were performed by injecting of fluorine 18 (18F)-labeled fluorodeoxyglucose (FDG) during resting breathing in normal control group and after applying the inspiratory resistance in another normal group. PET studies in severe COPD patients were only during resting breathing.We observed the activation sites and deactivation sites in the brain as follows.1)Dyspnea increased with increase in resistive loading in normal group. In normal group with resistive loaded breathing. The sites of precentral gyrus, postcentral gyrus, and orbital gyrus were activated, and the sites of precuneus, middle frontal gyrus, superior parietal lobe and cingulate gyrus were deactivated.2)In severe COPD patients, the sites of lingual gyrus, superior temporal gyrus, and orbital gyms were activated, and the sites of precuneus, cingulate gyrus, temporal lobe, superior parietal lobe and inferior parietal lobe were deactivated.3)Orbital gyrus was activated in both normal and COPD groups, and precuneus, cingulate gyms and superior parietal lobe were deactivated in both groups. The physiological meaning of the activation and deactivation in the brain observed in this study has not been clarified.