Li Muwei, Ding Zhaohua, Gore John C
Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232-2310, USA.
Cereb Cortex Commun. 2020;1(1):tgaa067. doi: 10.1093/texcom/tgaa067. Epub 2020 Sep 18.
Blood-oxygenation-level-dependent (BOLD) signals in magnetic resonance imaging indirectly reflect neural activity in cortex, but they are also detectable in white matter (WM). BOLD signals in WM exhibit strong correlations with those in gray matter (GM) in a resting state, but their interpretation and relationship to GM activity in a task are unclear. We performed a parametric visual object recognition task designed to modulate the BOLD signal response in GM regions engaged in higher order visual processing, and measured corresponding changes in specific WM tracts. Human faces embedded in different levels of random noise have previously been shown to produce graded changes in BOLD activation in for example, the fusiform gyrus, as well as in electrophysiological (N170) evoked potentials. The magnitudes of BOLD responses in both GM regions and selected WM tracts varied monotonically with the stimulus strength (noise level). In addition, the magnitudes and temporal profiles of signals in GM and WM regions involved in the task coupled strongly across different task parameters. These findings reveal the network of WM tracts engaged in object (face) recognition and confirm that WM BOLD signals may be directly affected by neural activity in GM regions to which they connect.
磁共振成像中基于血氧水平依赖（BOLD）的信号间接反映了皮质中的神经活动，但在白质（WM）中也可检测到。静息状态下，WM中的BOLD信号与灰质（GM）中的信号表现出很强的相关性，但其在任务中的解释以及与GM活动的关系尚不清楚。我们进行了一项参数化视觉物体识别任务，旨在调节参与高阶视觉处理的GM区域中的BOLD信号响应，并测量特定WM束中的相应变化。先前研究表明，嵌入不同程度随机噪声中的人脸会在例如梭状回以及电生理（N170）诱发电位中产生BOLD激活的分级变化。GM区域和选定WM束中BOLD反应的幅度均随刺激强度（噪声水平）单调变化。此外，参与任务的GM和WM区域中信号的幅度和时间特征在不同任务参数下紧密耦合。这些发现揭示了参与物体（面部）识别的WM束网络，并证实WM的BOLD信号可能直接受到它们所连接的GM区域中神经活动的影响。
