Electroconvulsive therapy (ECT) has been repeatedly linked to hippocampal plasticity. However, it remains unclear what role hippocampal plasticity plays in the antidepressant response to ECT. This magnetic resonance imaging (MRI) study tracks changes in separate hippocampal subregions and hippocampal networks in patients with depression (n = 44, 23 female) to determine their relationship, if any, with improvement after ECT. Voxelwise analyses were restricted to the hippocampus, amygdala, and parahippocampal cortex, and applied separately for responders and nonresponders to ECT. In analyses of arterial spin-labeled (ASL) MRI, nonresponders exhibited increased cerebral blood flow (CBF) in bilateral anterior hippocampus, while responders showed CBF increases in right middle and left posterior hippocampus. In analyses of gray matter volume (GMV) using T1-weighted MRI, GMV increased throughout bilateral hippocampus and surrounding tissue in nonresponders, while responders showed increased GMV in right anterior hippocampus only. Using CBF loci as seed regions, BOLD-fMRI data from healthy controls (n = 36, 19 female) identified spatially separable neurofunctional networks comprised of different brain regions. In graph theory analyses of these networks, functional connectivity within a hippocampus-thalamus-striatum network decreased only in responders after two treatments and after index. In sum, our results suggest that the location of ECT-related plasticity within the hippocampus may differ according to antidepressant outcome, and that larger amounts of hippocampal plasticity may not be conducive to positive antidepressant response. More focused targeting of hippocampal subregions and/or circuits may be a way to improve ECT outcome.

中文翻译：

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海马亚区和网络与电休克疗法的抗抑郁反应有关。

电休克疗法 (ECT) 已多次与海马可塑性相关联。然而，尚不清楚海马可塑性在 ECT 的抗抑郁反应中起什么作用。这项磁共振成像 (MRI) 研究跟踪了抑郁症患者（n = 44，其中 23 名女性）单独海马亚区和海马网络的变化，以确定它们与 ECT 后改善的关系（如果有的话）。体素分析仅限于海马体、杏仁核和海马旁皮质，并分别应用于 ECT 的反应者和无反应者。在动脉自旋标记 (ASL) MRI 分析中，无反应者表现出双侧前海马体的脑血流 (CBF) 增加，而反应者则显示右中和左后海马体的 CBF 增加。在使用 T1 加权 MRI 分析灰质体积 (GMV) 时，无反应者的双侧海马体和周围组织的 GMV 增加，而反应者仅在右前海马体中显示 GMV 增加。使用 CBF 基因座作为种子区域，来自健康对照（n = 36、19 名女性）的 BOLD-fMRI 数据确定了由不同大脑区域组成的空间可分离神经功能网络。在这些网络的图论分析中，海马体-丘脑-纹状体网络内的功能连通性仅在两次治疗后和指数后的反应者中下降。总而言之，我们的结果表明，海马内 ECT 相关可塑性的位置可能因抗抑郁结果而异，海马可塑性较大可能不利于积极的抗抑郁反应。