Kurzawski Jan W, Gulban Omer Faruk, Jamison Keith, Winawer Jonathan, Kay Kendrick
Department of Psychology, New York University, New York, New York 10003
Cognitive Neuroscience Department, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, 62229, The Netherlands.
J Neurosci. 2022 Sep 21;42(38):7256-7266. doi: 10.1523/JNEUROSCI.2532-21.2022.
To what extent is the size of the BOLD response influenced by factors other than neural activity? In a reanalysis of three neuroimaging datasets (male and female human participants), we find large systematic inhomogeneities in the BOLD response magnitude in primary visual cortex (V1): stimulus-evoked BOLD responses, expressed in units of percent signal change, are up to 50% larger along the representation of the horizontal meridian than the vertical meridian. To assess whether this surprising effect can be interpreted as differences in local neural activity, we quantified several factors that potentially contribute to the size of the BOLD response. We find relationships between BOLD response magnitude and cortical thickness, curvature, depth, and macrovasculature. These relationships are consistently found across subjects and datasets and suggest that variation in BOLD response magnitudes across cortical locations reflects, in part, differences in anatomy and vascularization. To compensate for these factors, we implement a regression-based correction method and show that, after correction, BOLD responses become more homogeneous across V1. The correction reduces the horizontal/vertical difference by about half, indicating that some of the difference is likely not because of neural activity differences. We conclude that interpretation of variation in BOLD response magnitude across cortical locations should consider the influence of the potential confounding factors of thickness, curvature, depth, and vascularization. The magnitude of the BOLD signal is often used as a surrogate of neural activity, but the exact factors that contribute to its strength have not been studied on a voxel-wise level. Here, we examined several anatomical and measurement-related factors to assess their relationship with BOLD signal magnitude. We find that BOLD magnitude correlates with cortical anatomy, depth, and macrovasculature. To remove the contribution of these factors, we propose a simple, data-driven correction method that can be used in any fMRI experiment. After accounting for the confounding factors, BOLD magnitude becomes more spatially homogeneous. Our correction method improves the ability to make more accurate inferences about local neural activity from fMRI data.
除神经活动外，其他因素在多大程度上影响了血氧水平依赖（BOLD）反应的大小？在对三个神经成像数据集（男性和女性人类参与者）进行重新分析时，我们发现初级视觉皮层（V1）中BOLD反应幅度存在很大的系统性不均匀性：以信号变化百分比为单位表示的刺激诱发BOLD反应，沿水平子午线的表征比垂直子午线大50%。为了评估这种惊人的效应是否可以解释为局部神经活动的差异，我们对几个可能影响BOLD反应大小的因素进行了量化。我们发现BOLD反应幅度与皮层厚度、曲率、深度和大血管结构之间存在关联。这些关联在不同受试者和数据集中一致存在，表明皮层不同位置的BOLD反应幅度变化部分反映了解剖结构和血管分布的差异。为了补偿这些因素，我们实施了一种基于回归的校正方法，结果表明，校正后，V1区域的BOLD反应变得更加均匀。校正使水平/垂直差异减少了约一半，这表明部分差异可能并非源于神经活动差异。我们得出结论，解释皮层不同位置BOLD反应幅度的变化时应考虑厚度、曲率、深度和血管分布等潜在混杂因素的影响。BOLD信号的大小常被用作神经活动的替代指标，但对其强度产生影响的确切因素尚未在体素水平上进行研究。在此，我们研究了几个解剖学和测量相关因素，以评估它们与BOLD信号大小的关系。我们发现BOLD大小与皮层解剖结构、深度和大血管结构相关。为了消除这些因素的影响，我们提出了一种简单的数据驱动校正方法，可用于任何功能磁共振成像（fMRI）实验。在考虑了混杂因素后，BOLD大小在空间上变得更加均匀。我们的校正方法提高了从fMRI数据中对局部神经活动做出更准确推断的能力。
