Interdisciplinary Program in Neuroscience, Georgetown University Medical Center Washington, DC, USA.
Department of Psychology, Georgetown University Washington, DC, USA.
Front Hum Neurosci. 2014 Feb 20;8:76. doi: 10.3389/fnhum.2014.00076. eCollection 2014.
Functional near-infrared spectroscopy (fNIRS) is an emerging low-cost noninvasive neuroimaging technique that measures cortical bloodflow. While fNIRS has gained interest as a potential alternative to fMRI for use with clinical and pediatric populations, it remains unclear whether fNIRS has the necessary sensitivity to serve as a replacement for fMRI. The present study set out to examine whether fNIRS has the sensitivity to detect linear changes in activation and functional connectivity in response to cognitive load, and functional connectivity changes when transitioning from a task-free resting state to a task. Sixteen young adult subjects were scanned with a continuous-wave fNIRS system during a 10-min resting-state scan followed by a letter n-back task with three load conditions. Five optical probes were placed over frontal and parietal cortices, covering bilateral dorsolateral PFC (dlPFC), bilateral ventrolateral PFC (vlPFC), frontopolar cortex (FP), and bilateral parietal cortex. Activation was found to scale linearly with working memory load in bilateral prefrontal cortex. Functional connectivity increased with increasing n-back loads for fronto-parietal, interhemispheric dlPFC, and local connections. Functional connectivity differed between the resting state scan and the n-back scan, with fronto-parietal connectivity greater during the n-back, and interhemispheric vlPFC connectivity greater during rest. These results demonstrate that fNIRS is sensitive to both cognitive load and state, suggesting that fNIRS is well-suited to explore the full complement of neuroimaging research questions and will serve as a viable alternative to fMRI.
功能性近红外光谱（fNIRS）是一种新兴的低成本非侵入性神经影像学技术，可测量皮质血流。虽然 fNIRS 作为 fMRI 的潜在替代品在临床和儿科人群中引起了关注，但它是否具有足够的灵敏度来替代 fMRI 仍不清楚。本研究旨在探讨 fNIRS 是否具有检测认知负荷下激活和功能连接线性变化的灵敏度，以及从无任务静息状态过渡到任务时功能连接的变化。16 名年轻成年受试者在连续波 fNIRS 系统下进行了 10 分钟的静息状态扫描，随后进行了字母 n 回任务，有三种负荷条件。五个光学探头放置在前额和顶叶皮层上，覆盖双侧背外侧前额叶皮层（dlPFC）、双侧腹外侧前额叶皮层（vlPFC）、额极皮层（FP）和双侧顶叶皮层。激活被发现与双侧前额叶皮层的工作记忆负荷呈线性关系。功能连接随着 n 回负荷的增加而增加，用于额顶叶、半球间 dlPFC 和局部连接。静息状态扫描和 n 回扫描之间的功能连接不同，n 回时额顶连接更大，静息时半球间 vlPFC 连接更大。这些结果表明，fNIRS 对认知负荷和状态都很敏感，这表明 fNIRS 非常适合探索神经影像学研究问题的全部内容，并将成为 fMRI 的可行替代品。
