Wu Xi, Yang Zhipeng, Bailey Stephen K, Zhou Jiliu, Cutting Laurie E, Gore John C, Ding Zhaohua
Department of Computer Science, Chengdu University of Information Technology, Chengdu 610225, PR China; Vanderbilt University Institute of Imaging Science, Nashville, TN 37232, United States.
Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States.
Neuroimage. 2017 May 15;152:371-380. doi: 10.1016/j.neuroimage.2017.02.074. Epub 2017 Mar 8.
Functional MRI has proven to be effective in detecting neural activity in brain cortices on the basis of blood oxygenation level dependent (BOLD) contrast, but has relatively poor sensitivity for detecting neural activity in white matter. To demonstrate that BOLD signals in white matter are detectable and contain information on neural activity, we stimulated the somatosensory system and examined distributions of BOLD signals in related white matter pathways. The temporal correlation profiles and frequency contents of BOLD signals were compared between stimulation and resting conditions, and between relevant white matter fibers and background regions, as well as between left and right side stimulations. Quantitative analyses show that, overall, MR signals from white matter fiber bundles in the somatosensory system exhibited significantly greater temporal correlations with the primary sensory cortex and greater signal power during tactile stimulations than in a resting state, and were stronger than corresponding measurements for background white matter both during stimulations and in a resting state. The temporal correlation and signal power under stimulation were found to be twice those observed from the same bundle in a resting state, and bore clear relations with the side of stimuli. These indicate that BOLD signals in white matter fibers encode neural activity related to their functional roles connecting cortical volumes, which are detectable with appropriate methods.
功能磁共振成像（Functional MRI）已被证明能基于血氧水平依赖（BOLD）对比有效地检测大脑皮质中的神经活动，但在检测白质中的神经活动方面灵敏度相对较差。为了证明白质中的BOLD信号是可检测的且包含神经活动信息，我们刺激了体感系统并检查了相关白质通路中BOLD信号的分布。比较了刺激和静息状态之间、相关白质纤维和背景区域之间以及左右侧刺激之间BOLD信号的时间相关曲线和频率成分。定量分析表明，总体而言，体感系统中白质纤维束的磁共振信号在触觉刺激期间与初级感觉皮层表现出显著更强的时间相关性，且信号功率高于静息状态，并且在刺激期间和静息状态下均强于背景白质的相应测量值。发现刺激下的时间相关性和信号功率是静息状态下同一纤维束观察值的两倍，并且与刺激侧有明确关系。这些表明白质纤维中的BOLD信号编码与其连接皮质区域的功能作用相关的神经活动，通过适当方法可检测到这些信号。
