Major depressive disorder (MDD) is often accompanied by severe impairments in working memory (WM). Neuroimaging studies investigating the mechanisms underlying these impairments have produced conflicting results. It remains unclear whether MDD patients show hyper- or hypoactivity in WM-related brain regions and how potential aberrations in WM processing may contribute to the characteristic dysregulation of cognition-emotion interactions implicated in the maintenance of the disorder. In order to shed light on these questions and to overcome limitations of previous studies, we applied a multivoxel pattern classification approach to investigate brain activity in large samples of MDD patients (N = 57) and matched healthy controls (N = 61) during a WM task that incorporated positive, negative, and neutral stimuli. Results showed that patients can be distinguished from healthy controls with good classification accuracy based on functional activation patterns. ROI analyses based on the classification weight maps showed that during WM, patients had higher activity in the left DLPFC and the dorsal ACC. Furthermore, regions of the default-mode network (DMN) were less deactivated in patients. As no performance differences were observed, we conclude that patients required more effort, indexed by more activity in WM-related regions, to successfully perform the task. This increased effort might be related to difficulties in suppressing task-irrelevant information reflected by reduced deactivation of regions within the DMN. Effects were most pronounced for negative and neutral stimuli, thus pointing toward important implications of aberrations in WM processes in cognition-emotion interactions in MDD.

中文翻译：

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严重抑郁症中异常的工作记忆处理：来自多体素模式分类的证据。

重度抑郁症（MDD）通常伴有工作记忆（WM）的严重损害。研究这些损伤的潜在机制的神经影像学研究产生了矛盾的结果。尚不清楚MDD患者在WM相关的大脑区域中是否表现出过度活跃或机能减退，以及WM加工中的潜在异常可能如何导致与维持该疾病有关的认知-情绪相互作用的特征失调。为了阐明这些问题并克服先前研究的局限性，我们在WM期间应用多体素模式分类方法研究了大样本MDD患者（N = 57）和匹配的健康对照组（N = 61）的大脑活动包含积极，消极和中性刺激的任务。结果表明，基于功能激活模式，可以以良好的分类准确度将患者与健康对照区分开。根据分类权重图进行的ROI分析显示，在WM期间，患者的左DLPFC和背侧ACC的活动较高。此外，患者的默认模式网络（DMN）区域的失活程度较小。由于未观察到性能差异，因此我们得出结论，患者需要更多的努力才能成功完成任务，并且需要在WM相关区域进行更多的活动来索引。这种增加的努力可能与抑制由DMN内区域的停用减少所反映的与任务无关的信息的困难有关。负面和中性刺激的影响最为明显，