Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
Neuropsychologia. 2012 Mar;50(4):479-86. doi: 10.1016/j.neuropsychologia.2011.07.007. Epub 2011 Jul 19.
The posterior parietal cortex, including the medial superior parietal lobule (mSPL), becomes transiently more active during acts of cognitive control in a wide range of domains, including shifts of spatial and nonspatial visual attention, shifts between working memory representations, and shifts between categorization rules. Furthermore, spatial patterns of activity within mSPL, identified using multivoxel pattern analysis (MVPA), reliably distinguish between different acts of control. Here we describe a novel multivoxel pattern-based analysis that uses fluctuations in cognitive state over time to reveal inter-regional functional connectivity. First, we used MVPA to model patterns of activity in mSPL associated with shifting or maintaining spatial attention. We then computed a multivoxel pattern time course (MVPTC) that reflects, moment-by-moment, the degree to which the pattern of activity in mSPL more closely matches an attention-shift pattern or a sustained-attention pattern. We then entered the MVPTC as a regressor in a univariate (i.e., voxelwise) general linear model (GLM) to identify voxels whose BOLD activity covaried with the MVPTC. This analysis revealed several regions, including the striatum of the basal ganglia and bilateral middle frontal gyrus, whose activity was significantly correlated with the MVPTC in mSPL. For comparison, we also conducted a conventional functional connectivity analysis, entering the mean BOLD time course in mSPL as a regressor in a univariate GLM. The latter analysis revealed correlations in extensive regions of the frontal lobes but not in any subcortical area. The MVPTC analysis provides greater sensitivity (e.g., revealing the striatal-mSPL connectivity) and greater specificity (i.e., revealing more-focal clusters) than a conventional functional connectivity analysis. We discuss the broad applicability of MVPTC analysis to a variety of neuroimaging contexts.
顶后皮质，包括内侧上顶叶（mSPL），在广泛的认知控制领域（包括空间和非空间视觉注意力的转移、工作记忆表示之间的转移以及分类规则之间的转移）中，其活动会暂时变得更加活跃。此外，使用多体素模式分析（MVPA）在 mSPL 内识别的活动空间模式可靠地区分不同的控制行为。在这里，我们描述了一种新的基于多体素模式的分析方法，该方法使用随时间变化的认知状态波动来揭示区域间功能连接。首先，我们使用 MVPA 来构建与转移或维持空间注意力相关的 mSPL 活动模式。然后，我们计算了一个多体素模式时间过程（MVPTC），该过程反映了 mSPL 活动模式与注意力转移模式或持续注意力模式的匹配程度。然后，我们将 MVPTC 作为一个回归量输入到单变量（即体素）一般线性模型（GLM）中，以识别与 MVPTC 活动模式相关的体素。该分析揭示了几个区域，包括基底神经节的纹状体和双侧额中回，其活动与 mSPL 中的 MVPTC 显著相关。相比之下，我们还进行了传统的功能连接分析，将 mSPL 中的平均 BOLD 时间过程作为回归量输入到单变量 GLM 中。后一种分析揭示了额叶广泛区域的相关性，但没有揭示任何皮质下区域。MVPTC 分析比传统的功能连接分析具有更高的灵敏度（例如，揭示纹状体与 mSPL 的连接）和更高的特异性（即，揭示更集中的簇）。我们讨论了 MVPTC 分析在各种神经影像学环境中的广泛适用性。
