BOLD fMRI identifies limbic, paralimbic, and cerebellar activation during air hunger
BOLD fMRI identifies limbic, paralimbic, and cerebellar activation during air hunger
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DOI：
10.1152/jn.2002.88.3.1500
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发表时间：
2002-09-01
影响因子：
2.5
通讯作者：
Corfield, DR
中科院分区：
文献类型：
--
作者：
Evans, KC;Banzett, RB;Corfield, DR
空气饥饿(不舒服的呼吸冲动)是呼吸困难(呼吸短促)的一个组成部分。三项人类(H2O)-O-15正电子发射断层扫描(PET)研究证实，在呼吸困难期间，边缘和边缘旁区域的系统发育古老结构被激活。其他研究表明，这些结构在其他感觉中被激活，这些感觉提醒机体注意紧急的动态平衡失衡：疼痛、口渴和对食物的饥饿。我们使用血氧水平依赖(BOLD)功能磁共振成像(FMRI)来检查空气饥饿时的激活。与正电子发射计算机断层扫描相比，功能磁共振成像有几个优势：增强的信噪比，更高的空间分辨率，以及没有电离辐射，使每个受试者都能进行更多的试验。6名健康男性和女性以12-14次/分钟的呼吸速度进行机械通气。初步实验在平均潮气末PCO(2)为41Torr。中重度空气饥饿发生在42-S低潮气量时期(平均0.75 L)。受试者将这种感觉描述为“像屏住呼吸一样”、“渴望呼吸”和“渴望呼吸”。在基线条件下，空气饥饿持续地被潮气量较大的时代缓解(平均值=1.47L)。同一受试者在轻度低碳酸血症(平均潮气末PCO(2)=33Torr)的背景下进行的对照实验采用了相似的潮气量，但没有引起空气饥饿，控制了与呼吸困难无关的刺激变量。在每个实验期间，我们保持恒定的呼气末PCO(2)和PO2，以避免全局脑血流的系统性变化。每5个S(T2*，56层，体素分辨率3x3x3 mm)采集一次全脑图像。与空气饥饿相关的激活通过基于体素的协方差交互分析来确定，该分析比较了初级实验和对照实验(SPM99)之间的数据。我们使用类似的空气饥饿刺激检测到了早期PET研究中没有看到的激活(Banzett等人。2000)。在本研究中激活的边缘和边缘旁区域位于前岛(在所有3个已发表的呼吸困难研究中均可见)、前扣带回、盖、小脑、杏仁核、丘脑和基底节。额顶叶注意网络的元素也被识别出来。在这项研究和所有已发表的研究中，前岛叶激活的一致性表明，岛叶对于呼吸困难的感觉是必不可少的，尽管目前的数据表明，岛叶与更大的神经网络协同作用。
Air hunger (uncomfortable urge to breathe) is a component of dyspnea (shortness of breath). Three human (H2O)-O-15 positron emission tomography (PET) studies have identified activation of phylogenetically ancient structures in limbic and paralimbic regions during dyspnea. Other studies have shown activation of these structures during other sensations that alert the organism to urgent homeostatic imbalance: pain, thirst, and hunger for food. We employed blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to examine activation during air hunger. fMRI conferred several advantages over PET: enhanced signal-to-noise, greater spatial resolution, and lack of ionizing radiation, enabling a greater number of trials in each subject. Six healthy men and women were mechanically ventilated at 12-14 breaths/min. The primary experiment was conducted at mean end-tidal Pco(2) of 41 Torr. Moderate to severe air hunger was evoked during 42-s epochs of lower tidal volume (mean = 0.75 L). Subjects described the sensation as "like breath-hold," "urge to breathe," and "starved for air." In the baseline condition, air hunger was consistently relieved by epochs of higher tidal volume (mean = 1.47 L). A control experiment in the same subjects under a background of mild hypocapnia (mean end-tidal Pco(2) = 33 Torr) employed similar tidal volumes but did not evoke air hunger, controlling for stimulus variables not related to dyspnea. During each experiment, we maintained constant end-tidal Pco(2) and PO2 to avoid systematic changes in global cerebral blood flow. Whole-brain images were acquired every 5 s (T2*, 56 slices, voxel resolution 3 x 3 x 3 mm). Activations associated with air hunger were determined using voxel-based interaction analysis of covariance that compared data between primary and control experiments (SPM99). We detected activations not seen in the earlier PET study using a similar air hunger stimulus (Banzett et al. 2000). Limbic and paralimbic loci activated in the present study were within anterior insula (seen in all 3 published studies of dyspnea), anterior cingulate, operculum, cerebellum, amygdala, thalamus, and basal ganglia. Elements of frontoparietal attentional networks were also identified. The consistency of anterior insular activation across subjects in this study and across published studies suggests that the insula is essential to dyspnea perception, although present data suggest that the insula acts in concert with a larger neural network.