Melbourne Neuropsychiatry Centre, The University of Melbourne, Australia.
Hum Brain Mapp. 2012 May;33(5):1089-106. doi: 10.1002/hbm.21270. Epub 2011 May 24.
Neuroimaging studies have consistently implicated alterations of the basal ganglia and orbitofrontal cortex in the pathophysiology of OCD, however, recent work also emphasizes more diffuse patterns of brain alteration as occurring in this disorder. The goal of this study was to extend such observations by investigating large-scale brain functional network correlates of cognitive-control performance in OCD patients.
We combined fMRI with a validated task of cognitive control and a multivariate statistical method to assess multiple functional networks encompassing broad task-relevant cortical regions in OCD patients and matched controls. Functional networks of interest were targeted a priori and the groups were compared in terms of the spatiotemporal profile of network responses (functional connectivity) during the task performance in a data-driven manner.
Task performance was equivalent in both groups and each distinct network demonstrated strong overlap in its general response during task. However, significant differences in functional connectivity were also observed between groups that appeared driven by specific phases of task performance. Such differences were most pronounced during rest-task transitions and mainly involved dorsal anterior cingulate and insular cortices within the paralimbic network. Relative heightened functional connectivity of insula in patients during task correlated with a measure of patients' state anxiety.
Our findings provide a novel functional imaging characterization of brain network alterations associated with cognitive-control in OCD. Additionally, these findings raise questions about the role of patients' arousal states on the performance of cognitive imaging tasks that are otherwise assumed to be emotionally neutral.
神经影像学研究一致表明，基底神经节和眶额皮层的改变与强迫症的病理生理学有关，但最近的研究也强调了这种疾病中更广泛的大脑改变模式。本研究的目的是通过研究强迫症患者认知控制表现的大规模大脑功能网络相关性来扩展这些观察结果。
我们将 fMRI 与认知控制的验证任务以及一种多变量统计方法相结合，以评估包括强迫症患者和匹配对照组广泛任务相关皮质区域的多个功能网络。目标是有兴趣的功能网络，并以数据驱动的方式比较两组在任务执行过程中网络反应（功能连接）的时空特征。
两组的任务表现相当，每个不同的网络在任务过程中都表现出强烈的一般反应重叠。然而，两组之间也观察到功能连接的显著差异，这些差异似乎是由任务特定阶段驱动的。这种差异在休息-任务转换期间最为明显，主要涉及边缘网络中的背侧前扣带皮层和岛叶。患者在任务期间岛叶的相对较高功能连接与患者状态焦虑的测量值相关。
我们的发现为强迫症患者认知控制相关大脑网络改变提供了新的功能影像学特征。此外，这些发现提出了关于患者唤醒状态对认知成像任务表现的作用的问题，而这些任务通常被认为是没有情绪的。
