Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA.
College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA.
J Physiol. 2024 Apr;602(8):1775-1790. doi: 10.1113/JP285568. Epub 2024 Mar 22.
Hypertension-related changes in brain function place individuals at higher risk for cognitive impairment and Alzheimer's disease. The existing functional neuroimaging literature has identified important neural and behavioural differences between normotensive and hypertensive individuals. However, previously-used methods (i.e. magnetic resonance imaging, functional near-infrared spectroscopy) rely on neurovascular coupling, which is a useful but indirect measure of neuronal activity. Furthermore, most studies fail to distinguish between controlled and uncontrolled hypertensive individuals, who exhibit significant behavioural and clinical differences. To partially remedy this gap in the literature, we used magnetoencephalography (MEG) to directly examine neuronal activity that is invariant to neurovascular coupling changes induced by hypertension. Our study included 52 participants (19 healthy controls, 15 controlled hypertensives, 18 uncontrolled hypertensives) who completed a modified flanker attention task during MEG. We identified significant oscillatory neural responses in two frequencies (alpha: 8-14 Hz, gamma: 48-60 Hz) for imaging and used grand-averaged images to determine seeds for whole-brain connectivity analysis. We then conducted Fisher-z tests for each pair of groups, using the relationship between the neural connectivity and behavioural attention effects. This highlighted a distributed network of regions associated with cognitive control and selective attention, including frontal-occipital and interhemispheric occipital connections. Importantly, the inferior frontal cortex exhibited a unique neurobehavioural relationship that distinguished the uncontrolled hypertensive group from the controlled hypertensive and normotensive groups. This is the first investigation of hypertension using MEG and identifies critical whole-brain connectivity differences based on hypertension profiles. KEY POINTS: Structural and functional changes in brain circuitry scale with hypertension severity and increase the risk of cognitive impairment and Alzheimer's disease. We harness the excellent spatiotemporal precision of magnetoencephalography (MEG) to directly quantify dynamic functional connectivity in healthy control, controlled hypertensive and uncontrolled hypertensive groups during a flanker task. In the first MEG study of hypertension, we show that there are neurobehavioural relationships that distinguish the uncontrolled hypertensive group from healthy and controlled hypertensive group in the prefrontal cortex. These results provide novel insights into the differential impact of hypertension on brain dynamics underlying selective attention.
高血压相关的大脑功能变化使个体更容易出现认知障碍和阿尔茨海默病。现有的功能神经影像学文献已经确定了正常血压个体和高血压个体之间存在重要的神经和行为差异。然而，以前使用的方法（即磁共振成像、功能近红外光谱）依赖于神经血管耦合，这是一种有用但间接的神经元活动测量方法。此外，大多数研究未能区分受控和不受控的高血压个体，他们表现出显著的行为和临床差异。为了部分弥补文献中的这一空白，我们使用脑磁图（MEG）直接检查不受高血压引起的神经血管耦合变化影响的神经元活动。我们的研究包括 52 名参与者（19 名健康对照者、15 名受控高血压者、18 名不受控高血压者），他们在 MEG 期间完成了改良的侧抑制注意任务。我们在两个频率（alpha：8-14 Hz，gamma：48-60 Hz）下识别出显著的振荡神经反应，并用平均图像确定全脑连接分析的种子。然后，我们对每组的每对进行 Fisher-z 检验，使用神经连接和行为注意效果之间的关系。这突出了与认知控制和选择性注意相关的区域的分布式网络，包括额枕部和半球间枕部连接。重要的是，下额前皮质表现出独特的神经行为关系，将不受控制的高血压组与受控的高血压组和正常血压组区分开来。这是首次使用 MEG 研究高血压，并根据高血压谱确定了关键的全脑连接差异。要点：大脑电路的结构和功能变化与高血压的严重程度成正比，并增加认知障碍和阿尔茨海默病的风险。我们利用脑磁图（MEG）出色的时空精度，直接量化健康对照组、受控高血压组和不受控高血压组在侧抑制任务期间的动态功能连接。在高血压的首次 MEG 研究中，我们表明，在前额皮质中，存在区分不受控制的高血压组与健康组和受控高血压组的神经行为关系。这些结果为高血压对选择性注意下大脑动力学的不同影响提供了新的见解。
