Stressful events impact memory formation, in particular for emotionally arousing stimuli. Although these stress effects on emotional memory formation have potentially far-reaching implications, the underlying neural mechanisms are not fully understood. Specifically, the temporal processing dimension of the mechanisms involved in emotional memory formation under stress remains elusive. Here, we used magnetoencephalography (MEG) to examine the neural processes underlying stress effects on emotional memory formation with high temporal and spatial resolution and a particular focus on theta oscillations previously implicated in mnemonic binding. Healthy participants (n = 53) underwent a stress or control procedure before encoding emotionally neutral and negative pictures, while MEG was recorded. Memory for the pictures was probed in a recognition test 24 h after encoding. In this recognition test, stress did not modulate the emotional memory enhancement but led to significantly higher confidence in memory for negative compared to neutral stimuli. Our neural data revealed that stress increased memory-related theta oscillations specifically in medial temporal and occipito-parietal regions. Further, this stress-related increase in theta power emerged during memory formation for emotionally negative but not for neutral stimuli. These findings indicate that acute stress can enhance, in the medial temporal lobe, oscillations at a frequency that is ideally suited to bind the elements of an ongoing emotional episode, which may represent a mechanism to facilitate the storage of emotionally salient events that occurred in the context of a stressful encounter.

压力事件会影响记忆的形成，尤其是情绪激动的刺激。尽管这些压力对情绪记忆形成的影响具有潜在的深远影响，但潜在的神经机制尚未完全了解。具体而言，压力下情绪记忆形成所涉及的机制的时间处理维度仍然难以捉摸。在这里，我们使用脑磁图 (MEG) 来检查压力对情绪记忆形成的潜在影响的神经过程，具有高时空分辨率，并特别关注先前与助记符绑定有关的 theta 振荡。健康参与者（n = 53）在编码情绪中性和负面图片之前经历压力或控制程序，同时记录 MEG。编码后 24 小时在识别测试中探测图片的记忆。在这个识别测试中，压力不会调节情绪记忆的增强，但与中性刺激相比，对负面记忆的信心显着提高。我们的神经数据显示，压力会增加与记忆相关的 theta 振荡，特别是在内侧颞叶和枕顶叶区域。此外，这种与压力相关的 theta 功率增加出现在记忆形成期间，对于消极情绪而不是中性刺激。这些发现表明，急性压力可以增强内侧颞叶的振荡，其频率非常适合结合正在进行的情绪发作的元素，