Introduction:

Electroconvulsive therapy (ECT) is a highly efficient treatment for depression. Previous studies repeatedly reported an ECT-induced volume increase in the hippocampi. We assume that this also affects extended hippocampal networks. This study aims to investigate the structural and functional interplay between hippocampi, hippocampal pathways and core regions of the default mode network (DMN). Twenty patients with a current depressive episode receiving ECT-treatment and twenty age and sex matched healthy controls (HC) were included in the study. ECT-patients underwent multimodal magnetic resonance imaging (MRI)-scans (diffusion weighted imaging, resting state functional MRI) before and after an ECT-index series. HC were also scanned twice in a similar between-scan time-interval. Parahippocampal cingulum (PHC) and uncinate fasciculus (UF) were reconstructed for each participant using manual tractography. Fractional anisotropy (FA) was averaged across tracts. Furthermore, we investigated seed-based functional connectivity (FC) from bilateral hippocampi and from the PCC, a core region of the DMN. At baseline, FA in PHC and UF did not differ between groups. There was no baseline group difference of hippocampal-FC. PCC-FC was decreased in ECT-patients. ECT induced a decrease in FA in the left PHC in the ECT group. No longitudinal changes of FA were found in the UF. Furthermore, there was a decrease in hippocampal-PCC-FC, an increase in hippocampal-supplementary motor area-FC, and an increase in PCC-FC in the ECT-group, reversing group differences at baseline. Our findings suggest that ECT induces structural and functional remodeling of a hippocampal-DMN. Those changes may contribute to ECT-induced clinical response in patients with depression.

中文翻译：

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电休克治疗诱导抑郁症患者海马与默认模式网络的共激活重塑

介绍：

电休克疗法（ECT）是治疗抑郁症的一种高效方法。之前的研究多次报道了 ECT 引起的海马体体积增加。我们假设这也会影响扩展的海马网络。本研究旨在研究海马、海马通路和默认模式网络（DMN）核心区域之间的结构和功能相互作用。该研究包括 20 名当前抑郁发作并接受 ECT 治疗的患者和 20 名年龄和性别匹配的健康对照 (HC)。ECT 患者在 ECT 指数系列之前和之后接受多模态磁共振成像 (MRI) 扫描（弥散加权成像、静息态功能 MRI）。HC 也以类似的扫描时间间隔扫描两次。使用手动纤维束成像重建每个参与者的海马旁扣带回（PHC）和钩束（UF）。分数各向异性 (FA) 是跨区域的平均值。此外，我们还研究了双侧海马和 PCC（DMN 的核心区域）的基于种子的功能连接（FC）。基线时，PHC 和 UF 中的 FA 在组间没有差异。海马-FC 没有基线组间差异。ECT 患者的 PCC-FC 降低。ECT 导致 ECT 组左侧 PHC 的 FA 减少。UF 中未发现 FA 纵向变化。此外，ECT 组中海马-PCC-FC 减少，海马补充运动区-FC 增加，PCC-FC 增加，逆转了基线时的组间差异。我们的研究结果表明 ECT 诱导海马 DMN 的结构和功能重塑。这些变化可能有助于 ECT 引起的抑郁症患者的临床反应。