应激普遍存在而且无法避免，多种不同类型的应激可影响大脑功能甚至导致认知和感情紊乱。应激对认知功能的影响非常复杂，受到多种因素如持续时间、作用模式以及具体认知功能的影响。海马的主要功能是学习记忆，其背侧神经网络是处理感觉信号的重要部位。海马腹侧则主要是和杏仁核之间传入传出的主要部位，可能对强化记忆的情绪反应十分关键。应激和应激激素对海马腹侧和背侧可产生不同的影响，慢性应激能削弱背侧的长时程激活，但不影响腹侧CA1区，提示应激在海马腹侧和背侧存在不同的应激作用模式。

应激对记忆的影响已经有许多研究，例如不同应激持续时间，急性应激对记忆功能的影响比慢性应激明显。但是，应激影响记忆的复杂性和重要性仍没有阐述清楚。由于慢性应激存在适应问题，因此常常采用不同的应激模式以获得足够的反应。那么，多种不同模式的应激和单一应激对学习记忆功能的影响和应激强度是否有关就是这一领域的重点问题。现代生活方式往往是多种心理、社会和躯体应激因素并存，因此这一问题具有很强的现实意义。最近有学者针对这个问题开展了一项动物实验研究，发现多种相对短时间应激类型比同样强度单一应激造成的记忆损害更严重。进一步研究发现两类应激模式对海马腹侧和背侧的影响也明显不同。多种应激和单纯束缚应激相比，虽然激素和下丘脑应激反应类似，但多种应激导致的海马病理损伤和记忆功能影响更明显，海马组织树突脊分析显示，背侧CA1突触损失明显，腹侧突触变化相对较少。脑内结构和神经回路受到的影响也明显不同。这些研究说明，多种类应激模式会通过影响海马背侧神经回路，影响大脑记忆功能。文章最近发表在Molecular Psychiatry。

A multimodal stress impacted memory differently than a more discrete stress. (a) Mice exposed to five hours of restraint stress were compared with those exposed to the same duration of a multimodal stress consisting of restraint, light, loud music and jostling. (b) During the testing phase of the novel object recognition task, the Discrimination index (DI) demonstrated that mice exposed to multimodal stress failed to distinguish the familiar object from a novel one. (c) Hormonal stress responses were comparable following restraint or multimodal stress. The levels and trajectories of plasma corticosterone at several time points after a restraint or a multimodal stress were indistinguishable. This was the case both at 1 h after the onset of stress, and at the 5-h time point (when stresses were terminated). n=3–5 per group per time point. (d) The total numbers of activated (Fos-ir) cells within the hypothalamic paraventricular nucleus were similar following restraint or multimodal stress, either 2 h from the onset of stress or at its termination (n=3–5 per group per time point). (e) Photomicrographs showing typical Fos staining within the PVN are quantified in d. Together, these data indicate that the two stress paradigms stimulate the neuroendocrine stress response system to a similar degree, that is, they do not differ in overall intensity. * signifies compared with stress-free controls, ^# signifies compared with restraint. 3v, third ventricle; f, fornix; PVN, paraventricular nucleus of the hypothalamus.