Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia; Monash Institute for Cognitive and Clinical Neurosciences, Monash University, Wellington Rd, Melbourne, 3800, Australia; Australian Research Council Centre of Excellence for Integrative Brain Function, 770 Blackburn Rd, Melbourne, 3800, Australia.
Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia; Department of Electrical and Computer Systems Engineering, Monash University, Wellington Rd, Melbourne, 3800, Australia.
Neuroimage. 2019 Apr 1;189:258-266. doi: 10.1016/j.neuroimage.2019.01.003. Epub 2019 Jan 4.
Studies of task-evoked brain activity are the cornerstone of cognitive neuroscience, and unravel the spatial and temporal brain dynamics of cognition in health and disease. Blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) is one of the most common methods of studying brain function in humans. BOLD-fMRI indirectly infers neuronal activity from regional changes in blood oxygenation and is not a quantitative metric of brain function. Regional variation in glucose metabolism, measured using [18-F] fluorodeoxyglucose positron emission tomography (FDG-PET), provides a more direct and interpretable measure of neuronal activity. However, while the temporal resolution of BOLD-fMRI is in the order of seconds, standard FDG-PET protocols provide a static snapshot of glucose metabolism. Here, we develop a novel experimental design for measurement of task-evoked changes in regional blood oxygenation and glucose metabolism with high temporal resolution. Over a 90-min simultaneous BOLD-fMRI/FDG-PET scan, [18F] FDG was constantly infused to 10 healthy volunteers, who viewed a flickering checkerboard presented in a hierarchical block design. Dynamic task-related changes in blood oxygenation and glucose metabolism were examined with temporal resolution of 2.5sec and 1-min, respectively. Task-related, temporally coherent brain networks of haemodynamic and metabolic connectivity were jointly coupled in the visual cortex, as expected. Results demonstrate that the hierarchical block design, together with the infusion FDG-PET technique, enabled both modalities to track task-related neural responses with high temporal resolution. The simultaneous MR-PET approach has the potential to provide unique insights into the dynamic haemodynamic and metabolic interactions that underlie cognition in health and disease.
任务诱发脑活动的研究是认知神经科学的基石，它揭示了健康和疾病状态下认知的空间和时间大脑动力学。血氧水平依赖功能磁共振成像（BOLD-fMRI）是研究人类大脑功能最常用的方法之一。BOLD-fMRI 从血氧的区域变化间接推断神经元活动，而不是大脑功能的定量指标。使用 [18-F] 氟脱氧葡萄糖正电子发射断层扫描（FDG-PET）测量的葡萄糖代谢的区域变化提供了神经元活动的更直接和可解释的度量。然而，虽然 BOLD-fMRI 的时间分辨率在秒的量级，但标准的 FDG-PET 方案提供了葡萄糖代谢的静态快照。在这里，我们开发了一种新的实验设计，用于以高时间分辨率测量任务诱发的区域血氧和葡萄糖代谢变化。在 90 分钟的同步 BOLD-fMRI/FDG-PET 扫描中，[18F]FDG 持续输注给 10 名健康志愿者，他们在层次块设计中观看闪烁的棋盘。分别以 2.5 秒和 1 分钟的时间分辨率检查血氧和葡萄糖代谢的动态任务相关变化。在视觉皮层中，预期会共同耦合与血液动力学和代谢连通性相关的任务相关、时间相干的大脑网络。结果表明，层次块设计与输注 FDG-PET 技术相结合，使两种模态都能够以高时间分辨率跟踪与任务相关的神经反应。这种同时的磁共振-正电子发射断层扫描方法有可能为健康和疾病状态下认知的动态血液动力学和代谢相互作用提供独特的见解。
