Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Switzerland; Department of Radiology and Medical Informatics, University of Geneva, Switzerland; Division of Development and Growth, Department of Pediatrics, University of Geneva, Switzerland.
Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Switzerland; Department of Radiology and Medical Informatics, University of Geneva, Switzerland.
Neuroimage. 2020 May 15;212:116635. doi: 10.1016/j.neuroimage.2020.116635. Epub 2020 Feb 25.
Investigating context-dependent modulations of Functional Connectivity (FC) with functional magnetic resonance imaging is crucial to reveal the neurological underpinnings of cognitive processing. Most current analysis methods hypothesise sustained FC within the duration of a task, but this assumption has been shown too limiting by recent imaging studies. While several methods have been proposed to study functional dynamics during rest, task-based studies are yet to fully disentangle network modulations. Here, we propose a seed-based method to probe task-dependent modulations of brain activity by revealing Psychophysiological Interactions of Co-activation Patterns (PPI-CAPs). This point process-based approach temporally decomposes task-modulated connectivity into dynamic building blocks which cannot be captured by current methods, such as PPI or Dynamic Causal Modelling. Additionally, it identifies the occurrence of co-activation patterns at single frame resolution as opposed to window-based methods. In a naturalistic setting where participants watched a TV program, we retrieved several patterns of co-activation with a posterior cingulate cortex seed whose occurrence rates and polarity varied depending on the context; on the seed activity; or on an interaction between the two. Moreover, our method exposed the consistency in effective connectivity patterns across subjects and time, allowing us to uncover links between PPI-CAPs and specific stimuli contained in the video. Our study reveals that explicitly tracking connectivity pattern transients is paramount to advance our understanding of how different brain areas dynamically communicate when presented with a set of cues.
用功能磁共振成像研究功能连接（FC）的上下文相关调制对于揭示认知处理的神经基础至关重要。大多数当前的分析方法假设任务持续时间内的持续 FC，但最近的成像研究表明，这种假设过于局限。虽然已经提出了几种方法来研究静息状态下的功能动态，但基于任务的研究尚未完全区分网络调制。在这里，我们提出了一种基于种子的方法，通过揭示共激活模式的心理生理相互作用（PPI-CAP）来探测大脑活动的任务依赖性调制。这种基于点过程的方法将任务调节的连通性分解为当前方法（如 PPI 或动态因果建模）无法捕捉的动态构建块。此外，它以单帧分辨率识别共激活模式的发生，而不是基于窗口的方法。在参与者观看电视节目的自然环境中，我们使用后扣带皮层种子检索到几种共激活模式，其发生频率和极性取决于上下文；种子活动；或两者之间的相互作用。此外，我们的方法揭示了跨主体和时间的有效连通性模式的一致性，使我们能够揭示 PPI-CAP 与视频中包含的特定刺激之间的联系。我们的研究表明，明确跟踪连通性模式的瞬态对于推进我们对不同大脑区域在呈现一组线索时如何动态通信的理解至关重要。
