Smirl Jonathan D, Wright Alexander D, Bryk Kelsey, van Donkelaar Paul
Sport Concussion Research Lab, University of British Columbia, Kelowna, BC, Canada.
Sport Concussion Research Lab, University of British Columbia, Kelowna, BC, Canada; MD/PhD Program, University of British Columbia, Vancouver, BC, Canada; Department of Experimental Medicine, University of British Columbia, Vancouver, BC, Canada; Southern Medical Program, University of British Columbia, Kelowna, BC, Canada.
J Neurosci Methods. 2016 Sep 1;270:92-101. doi: 10.1016/j.jneumeth.2016.06.007. Epub 2016 Jun 9.
The concept of neurovascular coupling has been postulated since the late 1800s and has been demonstrated most commonly in humans using visual stimuli (e.g. reading, checkerboards). These traditional paradigms evoke only a moderate cerebral blood flow response due to the relative simplicity of the visual stimuli.
Forty subjects completed three visual paradigms each challenging the visual processing areas to a different extent: reading text, complicated visual searching (new method: Where's Waldo) and viewing coloured dots. Posterior and middle cerebral artery (PCA, MCA) velocities were recorded using transcranial Doppler ultrasound during each visual paradigm.
Prior to the presentation of the visual stimuli there were no differences in mean arterial pressure, or PCA or MCA velocities for the three paradigms. All three paradigms led to an elevation in PCA and MCA velocities after a delay (∼1.1s). Whereas velocity elevation was consistent across the three paradigms in the MCA, it was markedly larger during the Where's Waldo task in the PCA. Thus, although the onset of the neurovascular coupling response was similar across the three visual paradigms, its overall magnitude was stimulus-dependent.
Given that PCA velocity can be affected by blood pressure or carbon dioxide alterations, traditional neurovascular coupling paradigms (e.g. reading, checkerboards) appear to have a lower signal-to-noise ratio than that observed in complicated visual search tasks such as Where's Waldo.
We recommend complicated visual search paradigms such as Where's Waldo be considered for future transcranial Doppler-based neurovascular coupling studies.
自19世纪末以来就有人提出神经血管耦合的概念，在人类中最常用视觉刺激（如阅读、棋盘）来证明这一概念。由于视觉刺激相对简单，这些传统范式仅引起适度的脑血流反应。
40名受试者完成了三种视觉范式，每种范式对视觉处理区域的挑战程度不同：阅读文本、复杂视觉搜索（新方法：《威利在哪里》）和观看彩色圆点。在每种视觉范式期间，使用经颅多普勒超声记录大脑后动脉和大脑中动脉（PCA、MCA）的血流速度。
在呈现视觉刺激之前，三种范式的平均动脉压、PCA或MCA血流速度没有差异。所有三种范式在延迟（约1.1秒）后均导致PCA和MCA血流速度升高。虽然MCA中三种范式的血流速度升高是一致的，但在PCA中，《威利在哪里》任务期间的升高明显更大。因此，尽管三种视觉范式的神经血管耦合反应开始时间相似，但其总体幅度取决于刺激。
鉴于PCA血流速度会受到血压或二氧化碳变化的影响，传统的神经血管耦合范式（如阅读、棋盘）的信噪比似乎低于复杂视觉搜索任务（如《威利在哪里》）中观察到的信噪比。
我们建议在未来基于经颅多普勒的神经血管耦合研究中考虑使用复杂视觉搜索范式，如《威利在哪里》。
