Stressful events affect mnemonic processing, in particular for emotionally arousing events. Previous research on the mechanisms underlying stress effects on human memory focused on stress-induced changes in the neural activity elicited by a stimulus. We tested an alternative mechanism and hypothesized that stress may already alter the neural context for successful memory formation, reflected in the neural activity preceding a stimulus. Therefore, 69 participants underwent a stress or control procedure before encoding neutral and negative pictures. During encoding, we recorded high-density EEG and analyzed—based on multivariate searchlight analyses—oscillatory activity and cross-frequency coupling patterns before stimulus onset that were predictive of memory tested 24 hr later. Prestimulus theta predicted subsequent memory in controls but not in stressed participants. Instead, prestimulus gamma predicted successful memory formation after stress, specifically for emotional material. Likewise, stress altered the patterns of prestimulus theta–beta and theta–gamma phase–amplitude coupling predictive of subsequent memory, again depending on the emotionality of the presented material. Our data suggest that stress changes the neural context for building new memories, tuning this neural context specifically to the encoding of emotionally salient events. These findings point to a yet unknown mechanism through which stressful events may change (emotional) memory formation.

压力事件会影响记忆处理，尤其是情绪激动事件。先前关于压力对人类记忆影响的机制的研究集中在压力引起的刺激引起的神经活动的变化上。我们测试了另一种机制，并假设压力可能已经改变了成功记忆形成的神经环境，反映在刺激之前的神经活动中。因此，69 名参与者在编码中性和负面图片之前经历了压力或控制程序。在编码过程中，我们记录了高密度 EEG 并基于多变量探照灯分析分析了刺激开始前的振荡活动和交叉频率耦合模式，这些模式可预测 24 小时后测试的记忆。Prestimulus theta 预测了对照组的后续记忆，而不是压力参与者的记忆。相反，刺激前伽玛预测压力后成功的记忆形成，特别是对于情绪材料。同样，压力改变了预刺激的模式 theta-beta 和 theta-gamma 相位-幅度耦合预测后续记忆，同样取决于所呈现材料的情绪。我们的数据表明，压力会改变构建新记忆的神经环境，调整这种神经环境，专门针对情绪显着事件的编码。这些发现指出了一种未知的机制，压力事件可能通过该机制改变（情绪）记忆的形成。压力改变了预刺激的模式 theta-beta 和 theta-gamma 相位-幅度耦合预测后续记忆，这同样取决于所呈现材料的情绪。我们的数据表明，压力会改变构建新记忆的神经环境，调整这种神经环境，专门针对情绪显着事件的编码。这些发现指出了一种未知的机制，压力事件可能通过该机制改变（情绪）记忆的形成。压力改变了预刺激的模式 theta-beta 和 theta-gamma 相位-幅度耦合预测后续记忆，这同样取决于所呈现材料的情绪。我们的数据表明，压力会改变构建新记忆的神经环境，调整这种神经环境，专门针对情绪显着事件的编码。这些发现指出了一种未知的机制，压力事件可能通过该机制改变（情绪）记忆的形成。