Tsvetanov Kamen A, Henson Richard N A, Rowe James B
Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0SZ, UK.
Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK.
Philos Trans R Soc Lond B Biol Sci. 2021 Jan 4;376(1815):20190631. doi: 10.1098/rstb.2019.0631. Epub 2020 Nov 16.
Accurate identification of brain function is necessary to understand the neurobiology of cognitive ageing, and thereby promote well-being across the lifespan. A common tool used to investigate neurocognitive ageing is functional magnetic resonance imaging (fMRI). However, although fMRI data are often interpreted in terms of neuronal activity, the blood oxygenation level-dependent (BOLD) signal measured by fMRI includes contributions of both vascular and neuronal factors, which change differentially with age. While some studies investigate vascular ageing factors, the results of these studies are not well known within the field of neurocognitive ageing and therefore vascular confounds in neurocognitive fMRI studies are common. Despite over 10 000 BOLD-fMRI papers on ageing, fewer than 20 have applied techniques to correct for vascular effects. However, neurovascular ageing is not only a confound in fMRI, but an important feature in its own right, to be assessed alongside measures of neuronal ageing. We review current approaches to dissociate neuronal and vascular components of BOLD-fMRI of regional activity and functional connectivity. We highlight emerging evidence that vascular mechanisms in the brain do not simply control blood flow to support the metabolic needs of neurons, but form complex neurovascular interactions that influence neuronal function in health and disease. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
准确识别脑功能对于理解认知衰老的神经生物学机制从而促进整个人生阶段的健康幸福至关重要。一种用于研究神经认知衰老的常用工具是功能磁共振成像（fMRI）。然而，尽管fMRI数据常常根据神经元活动来解释，但fMRI测量的血氧水平依赖（BOLD）信号包含了血管和神经元因素的贡献，而这些因素随年龄的变化各不相同。虽然一些研究调查了血管衰老因素，但这些研究的结果在神经认知衰老领域并不广为人知，因此神经认知fMRI研究中的血管混杂因素很常见。尽管有超过10000篇关于衰老的BOLD-fMRI论文，但应用技术来校正血管效应的论文不到20篇。然而，神经血管衰老不仅是fMRI中的一个混杂因素，其本身也是一个重要特征，需要与神经元衰老的测量指标一起进行评估。我们综述了当前区分区域活动和功能连接的BOLD-fMRI中神经元和血管成分的方法。我们强调新出现的证据表明，大脑中的血管机制不仅仅是控制血流以支持神经元的代谢需求，而是形成了复杂的神经血管相互作用，这些相互作用在健康和疾病状态下都会影响神经元功能。本文是主题为“非侵入性功能神经成像与潜在神经元活动之间的关键关系”的一部分。
