Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.
Magn Reson Imaging. 2013 Nov;31(9):1492-500. doi: 10.1016/j.mri.2013.07.005. Epub 2013 Aug 19.
The task induced blood oxygenation level dependent signal changes observed using functional magnetic resonance imaging (fMRI) are critically dependent on the relationship between neuronal activity and hemodynamic response. Therefore, understanding the nature of neurovascular coupling is important when interpreting fMRI signal changes evoked via task. In this study, we used regional homogeneity (ReHo), a measure of local synchronization of the BOLD time series, to investigate whether the similarities of one voxel with the surrounding voxels are a property of neurovascular coupling. FMRI scans were obtained from fourteen subjects during bilateral finger tapping (FTAP), digit-symbol substitution (DSST) and periodic breath holding (BH) paradigm. A resting-state scan was also obtained for each of the subjects for 4min using identical imaging parameters. Inter-voxel correlation analyses were conducted between the resting-state ReHo, resting-state amplitude of low frequency fluctuations (ALFF), BH responses and task activations within the masks related to task activations. There was a reliable mean voxel-wise spatial correlation between ReHo and other neurovascular variables (BH responses and ALFF). We observed a moderate correlation between ReHo and task activations (FTAP: r=0.32; DSST: r=0.22) within the task positive network and a small yet reliable correlation within the default mode network (DSST: r=-0.08). Subsequently, a linear regression was used to estimate the contribution of ReHo, ALFF and BH responses to the task activated voxels. The unique contribution of ReHo was minimal. The results suggest that regional synchrony of the BOLD activity is a property that can explain the variance of neurovascular coupling and task activations; but its contribution to task activations can be accounted for by other neurovascular factors such as the ALFF.
任务诱发的血氧水平依赖信号变化在功能磁共振成像（fMRI）中观察到，这与神经元活动与血液动力学反应之间的关系密切相关。因此，在解释通过任务引起的 fMRI 信号变化时，了解神经血管耦合的性质非常重要。在这项研究中，我们使用局部一致性（ReHo），一种测量 BOLD 时间序列局部同步性的方法，来研究一个体素与周围体素的相似性是否是神经血管耦合的特性。我们对 14 名受试者在双侧手指敲击（FTAP）、数字符号替换（DSST）和周期性呼吸暂停（BH）范式期间进行了 fMRI 扫描。还为每个受试者在相同的成像参数下获得了 4 分钟的静息状态扫描。在任务激活的掩模内，对静息状态 ReHo、静息状态低频波动幅度（ALFF）、BH 反应和任务激活之间的体素间相关性进行了分析。ReHo 与其他神经血管变量（BH 反应和 ALFF）之间存在可靠的平均体素空间相关性。我们观察到 ReHo 与任务激活之间存在中等程度的相关性（FTAP：r=0.32；DSST：r=0.22），在任务正网络内，在默认模式网络内存在小但可靠的相关性（DSST：r=-0.08）。随后，我们使用线性回归来估计 ReHo、ALFF 和 BH 反应对任务激活体素的贡献。ReHo 的独特贡献很小。结果表明，BOLD 活动的区域同步性是可以解释神经血管耦合和任务激活方差的特性；但它对任务激活的贡献可以由其他神经血管因素（如 ALFF）来解释。
