Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
Neuroimage. 2014 Aug 15;97:349-62. doi: 10.1016/j.neuroimage.2014.04.022. Epub 2014 Apr 15.
Decreases in stimulus-dependent blood oxygenation level dependent (BOLD) signal and their underlying neurovascular origins have recently gained considerable interest. In this study a multi-echo, BOLD-corrected vascular space occupancy (VASO) functional magnetic resonance imaging (fMRI) technique was used to investigate neurovascular responses during stimuli that elicit positive and negative BOLD responses in human brain at 7 T. Stimulus-induced BOLD, cerebral blood volume (CBV), and cerebral blood flow (CBF) changes were measured and analyzed in 'arterial' and 'venous' blood compartments in macro- and microvasculature. We found that the overall interplay of mean CBV, CBF and BOLD responses is similar for tasks inducing positive and negative BOLD responses. Some aspects of the neurovascular coupling however, such as the temporal response, cortical depth dependence, and the weighting between 'arterial' and 'venous' contributions, are significantly different for the different task conditions. Namely, while for excitatory tasks the BOLD response peaks at the cortical surface, and the CBV change is similar in cortex and pial vasculature, inhibitory tasks are associated with a maximum negative BOLD response in deeper layers, with CBV showing strong constriction of surface arteries and a faster return to baseline. The different interplays of CBV, CBF and BOLD during excitatory and inhibitory responses suggests different underlying hemodynamic mechanisms.
最近，刺激依赖性血氧水平依赖（BOLD）信号的减少及其潜在的神经血管起源引起了相当大的关注。在这项研究中，使用多回波、BOLD 校正血管空间占有率（VASO）功能磁共振成像（fMRI）技术，在 7T 下研究了在人类大脑中引起正 BOLD 和负 BOLD 反应的刺激期间的神经血管反应。在宏观和微血管的“动脉”和“静脉”血液隔间中测量和分析了刺激诱导的 BOLD、脑血容量（CBV）和脑血流（CBF）变化。我们发现，对于引起正 BOLD 和负 BOLD 反应的任务，平均 CBV、CBF 和 BOLD 反应的整体相互作用是相似的。然而，神经血管耦合的某些方面，如时间响应、皮层深度依赖性以及“动脉”和“静脉”贡献之间的权重，对于不同的任务条件有很大的不同。具体而言，虽然对于兴奋性任务，BOLD 反应在皮层表面达到峰值，CBV 变化在皮层和软脑膜血管中相似，但抑制性任务与深层的最大负 BOLD 反应相关联，CBV 显示出表面动脉的强烈收缩，并且更快地回到基线。兴奋性和抑制性反应过程中 CBV、CBF 和 BOLD 的不同相互作用表明存在不同的潜在血液动力学机制。
