Brain-Body Interaction of Breath-by-Breath O2-CO2 Exchange Ratio withResting State Cerebral Hemodynamic Fluctuations

7.项目概要/摘要（不超过30行） 脑血流动力学低频波动（低于0.05Hz）的起源 默认模式网络（DMN）和其他静止状态网络（RSN）仍然未知。我们假设 低频率的CHF与静息全身代谢的波动相关， 自主呼吸中呼吸气体交换测量（O2摄取、CO2释放及其比率）。 我们介绍了一种新的脑-体相互作用，显示CHF和呼吸之间的强相关性 O2-CO2交换率（bER），是O2吸收与CO2释放的比率。经颅多普勒 超声检查和功能性磁共振成像显示，bER优于O2摄取， 与CHF的相关性远好于CO2释放。O2吸收优于CO2吸收 释放表明O2吸收和CO2释放与CHF的相关性不是多余的。的 在0.03 ~ 0.008Hz频率范围内，bER与CHF的相关性显著 随着相干性在越来越低的频率下变得越来越强。大脑区域具有强 bER-CHF耦合与默认模式网络（DMN）的许多区域重叠，表明可能存在 以bER为特征的静息全身代谢振荡与 以DMN为特征的背景脑活动。我们建议研究60名正常人， 神经影像学数据库，以提高我们对bER-CHF耦合的作用，脑-体 全身代谢和静息状态脑活动之间的相互作用，尤其是在DMN时。这样的 数据库的建立不仅为进一步研究DMN的基本机制和其他脑静息状态提供了基础 振荡，但也为未来的临床研究提供了机会， 其调节呼吸气体交换以用于诊断以及治疗目的。

7. Project Summary/Abstract (No more than 30 lines) The origin of the low frequencies (below 0.05Hz) resting state cerebral hemodynamic fluctuations (CHF) in default mode network (DMN) and other resting state networks (RSNs) remains unknown. We hypothesized that CHF at low frequencies correlated with fluctuations in resting systemic metabolism obtained from respiratory gas exchange measurements (O2 uptake, CO2 release and their ratio) in spontaneous breathing. We introduced a new brain-body interaction showing a strong correlation between CHF and breath-by-breath O2-CO2 exchange ratio (bER) which is a ratio of O2 uptake to CO2 release. With transcranial Doppler sonography and functional magnetic resonance imaging, bER was shown to be better than O2 uptake which in turn was far better than CO2 release in correlation with CHF. The superiority of O2 uptake over that of CO2 release indicates that O2 uptake and CO2 release are not redundant in their correlation with CHF. The coherence of bER with CHF was shown to be significant at the frequency range between 0.03Hz and 0.008Hz with the coherence getting stronger and stronger at lower and lower frequencies. Brain regions with strong bER-CHF coupling overlapped many areas of the default mode network (DMN), suggesting a potential association between oscillations of resting systemic metabolism characterized by bER and the rhythm of background brain activities characterized by DMN. We propose to study 60 normal individuals to increase our neuroimaging data base to improve our understanding on the role of bER-CHF coupling, a brain-body interaction between systemic metabolism and resting state brain activities, especially those at DMN. Such a data base will not only support more research on the basic mechanism of DMN and other cerebral resting state oscillations but also provide opportunities for future clinical research which images brain markers for conditions that modulate respiratory gas exchange for diagnostic as well as therapeutic purposes.