Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China.
Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China.
Brain Struct Funct. 2017 Dec;222(9):4065-4077. doi: 10.1007/s00429-017-1449-4. Epub 2017 Jun 9.
Hyperthermia may impair vigilance functions and lead to slower reaction times (RTs) in the psychomotor vigilance task (PVT) and possibly disturbing cerebral hemodynamic rhythms. To test these hypotheses, we acquired the resting-state BOLD and cerebral blood flow (CBF) data, as well as PVTRTs from 15 participants in two simulated environmental thermal conditions (50 °C/25 °C). We adopted a data-driven method, frequency component analysis, to quantify the mean frequency of the BOLD series of each voxel. Across-subject correlation analysis was employed to detect the brain areas whose BOLD oscillation frequency was correlated with the RTs. Significant changes of BOLD frequency and CBF within these areas were compared between hyperthermia and normothermia conditions. Spatial correlations between BOLD frequency and CBF were calculated within different brain areas for each subject under both thermal conditions. Results showed that, under both thermal conditions, the RTs correlated with the BOLD frequency positively in the default mode network (DMN) and negatively in the sensorimotor network (SMN). The increase of BOLD frequency in the thalamus and ventral medial prefrontal cortex was correlated with the increase of RTs in hyperthermia compared with normothermia. Hyperthermia decreased BOLD frequency and CBF in the SMN, while it increased CBF in the thalamus and posterior cingulate. In both thermal conditions, the spatial distribution of CBF negatively correlated with the spatial distribution of BOLD oscillation frequency in most cortical areas, especially in cingulate cortices, precuneus, and primary visual cortex. These results suggest that hyperthermia might deteriorate task performance by interfering with the resting-state CBF, and with BOLD rhythms. The overlapping of the thermoregulatory and vigilance functions in the SMN and DMN might underlie the neural mechanisms of the cognitive-behavioral impairments induced by hyperthermia.
过热可能会损害警觉功能，并导致精神运动警觉任务（PVT）中的反应时间（RT）变慢，可能还会扰乱大脑血液动力学节律。为了验证这些假设，我们在两种模拟环境热条件（50°C/25°C）下，从 15 名参与者中获得了静息状态 BOLD 和脑血流（CBF）数据以及 PVT-RTs。我们采用了一种数据驱动的方法，即频率分量分析，以量化每个体素的 BOLD 序列的平均频率。采用跨被试相关性分析来检测与 RT 相关的 BOLD 振荡频率的大脑区域。比较了过热和正常体温条件下这些区域内的 BOLD 频率和 CBF 的变化。在两种热条件下，为每个被试计算了不同脑区的 BOLD 频率和 CBF 之间的空间相关性。结果表明，在两种热条件下，RT 与默认模式网络（DMN）中的 BOLD 频率呈正相关，与感觉运动网络（SMN）中的 BOLD 频率呈负相关。与正常体温相比，过热时丘脑和腹内侧前额叶皮层的 BOLD 频率增加与 RT 增加相关。过热时，SMN 中的 BOLD 频率和 CBF 降低，而丘脑和后扣带回的 CBF 增加。在两种热条件下，CBF 的空间分布与大多数皮质区域的 BOLD 振荡频率的空间分布呈负相关，尤其是扣带回皮质、楔前叶和初级视觉皮层。这些结果表明，过热可能通过干扰静息状态 CBF 和 BOLD 节律来恶化任务表现。SMN 和 DMN 中的体温调节和警觉功能的重叠可能是过热引起的认知行为障碍的神经机制的基础。
