Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada.
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
Brain Imaging Behav. 2020 Dec;14(6):2438-2449. doi: 10.1007/s11682-019-00194-5.
The purpose of this study was to quantify differences in blood oxygen level dependent (BOLD) activation on a working memory task, baseline cerebral blood flow (CBF), and cerebrovascular reactivity (CVR) between participants with and without a history of concussion. A dual-echo pseudo-continuous arterial spin labelling (pCASL) sequence was performed on a group of 10 subjects with a previous concussion (126 ± 15 days prior) and on a control group (n = 10) during a visual working memory protocol. A separate dual-echo pCASL sequence was used to derive CVR and CBF measurements from a boxcar hypercapnic breathing protocol. Brain areas with significant activation differences on the working memory task between groups were identified and combined as an aggregate region of interest for CBF and CVR analyses. Areas of reduced BOLD activation during the working memory task in the concussed group included the ventral anterior cingulate cortex (ACC), the medial temporal gyrus (MTG), and the lateral occipital cortex in two loci. A single area of increased activation was located in the parietal operculum. Further analyses of CBF and CVR in these regions revealed reduced CVR in the concussed group in the MTG and ACC, while CBF did not differ. The differences in CVR between the two groups in these regions suggest that concussive injury may result in microvascular dysfunction. In turn, the decreased BOLD response during the task could be due to altered neurovascular coupling, rather than an impairment in neural activation alone. However, in other regions associated with working memory, unchanged CBF and CVR suggests that neural injury also persists after concussion. In the future, BOLD results should be normalized to CVR in order achieve a clearer understanding of the neural and vascular contributions to the differences in the signal.
本研究旨在量化有和无既往脑震荡史的参与者在执行工作记忆任务时血氧水平依赖（BOLD）激活、基线脑血流（CBF）和脑血管反应性（CVR）方面的差异。对一组有既往脑震荡史的受试者（126±15 天前）和对照组（n=10）进行了双回波伪连续动脉自旋标记（pCASL）序列，以进行视觉工作记忆协议。使用单独的双回波 pCASL 序列，从箱式高碳酸呼吸协议中得出 CVR 和 CBF 测量值。确定了组间工作记忆任务中具有显著激活差异的脑区，并将其组合为 CBF 和 CVR 分析的感兴趣区。在脑震荡组中，执行工作记忆任务时 BOLD 激活减少的区域包括腹侧前扣带皮层（ACC）、内侧颞叶（MTG）和外侧枕叶两个部位。一个激活增加的区域位于顶叶脑岛。进一步分析这些区域的 CBF 和 CVR 发现，脑震荡组 MTG 和 ACC 中的 CVR 降低，而 CBF 没有差异。这些区域中两组间 CVR 的差异表明，脑震荡性损伤可能导致微血管功能障碍。反过来，任务期间 BOLD 反应的降低可能是由于神经血管耦联改变，而不仅仅是神经激活的损伤。然而，在与工作记忆相关的其他区域，CBF 和 CVR 不变表明，神经损伤也在脑震荡后持续存在。在未来，BOLD 结果应归一化为 CVR，以便更清楚地了解信号差异中神经和血管的贡献。
