Hormones and Learning and Memory

任何经历过青春期、怀孕或衰老的人都可以证明：激素可以对大脑和行为产生强大的影响。我与 NSERC 相关的研究重点是激素和生物性别如何影响大脑从而影响学习和记忆。为什么要研究记忆力的性别差异？男性和女性出现记忆问题的易感性不同，并且大脑对记忆的反应也不同。例如，男性更有可能因精神分裂症而出现记忆问题，而女性则更有可能因抑郁症而出现记忆问题，或者因阿尔茨海默病而出现更严重的记忆丧失。因此，为了更好地了解两性的记忆是如何形成的，重要的是要承认和研究两性之间对记忆的反应可能出现的差异。此外，雌激素，特别是雌二醇，可以对记忆产生深远的影响。关于使用雌激素促进女性认知存在很多争议，这可能是由于文献中相互矛盾的报道所致。我们发现雌二醇是最强大的雌激素，它对学习和记忆的影响不同，具体取决于记忆任务和雌二醇的用量。高水平的雌二醇会损害工作记忆（每次试验都会变化的记忆，即每天把车停在哪里）和参考记忆（随着时间的推移保持稳定的记忆，即停车场在哪里）。然而，低水平的雌二醇有利于工作记忆。这些发现表明，雌二醇对学习有不同的影响，具体取决于剂量，对工作记忆有积极影响，但对参考记忆有不利影响。海马体是负责记忆的重要大脑区域，在啮齿动物和人类的整个生命周期中都会产生新的脑细胞，这些新细胞在不同形式的记忆中发挥着至关重要的作用。我们发现男性和女性海马体对记忆的反应不同，并且当女性雌激素水平不同时，我们发现新细胞的产生也存在差异。这些发现表明，两性之间和/或不同雌二醇水平涉及学习和记忆的途径不同。在这项提案中，我们计划研究这两个因素（性别和雌二醇）如何影响大脑中学习和记忆发生的位置和方式。我们将研究 1) 记忆后海马体和其他大脑区域的激活，2) 新脑细胞如何对记忆做出反应，以及 3) 男性和女性或雌二醇水平不同的女性中驱动记忆的脑细胞机制是否不同。了解生物性别和激素如何影响记忆，可能有助于更好地理解男性和女性大脑中学习和记忆的组织方式，并最终了解为什么有些人比其他人更容易出现记忆问题。

As anyone who has gone through adolescence, pregnancy, or aging can attest: hormones can exert powerful effects on brain and behaviour. My NSERC-related research has focussed on how hormones and biological sex can affect the brain to influence learning and memory. Why study sex differences in memory? Men and women differ in their susceptibility to develop memory problems, and show different brain responses to memory. For example, men are more likely to have memory problems with schizophrenia whereas women are more likely to have memory problems with depression or more severe memory loss with Alzheimer's disease. Hence, to gain a better understanding of how memories are formed in both sexes, it is important to acknowledge and study differences that might arise between both sexes in response to memory. Furthermore, estrogens, particularly estradiol, can exert profound effects on memory. There is a lot of controversy surrounding the use of estrogens to promote cognition in women, likely due to conflicting reports in the literature. We have found that estradiol, the most powerful of the estrogens, affects learning and memory differentially depending on the memory task and the amount estradiol given. High levels of estradiol impair both working (memory that changes from trial to trial, i.e. where you park your car every day) and reference memory (memory that stay stable over time, i.e where the parking lot is). However, low levels of estradiol facilitate working memory. These findings suggest that estradiol has different effects on learning dependent on the dose given with positive effects on working memory but detrimental effects on reference memory. The hippocampus, an important brain area for memory, produces new brain cells throughout the lifespan in rodents and humans and these new cells play a crucial role in different forms of memory. We found that males and females differ in the hippocampus's response to memory, as well as we see differences in the production of new cells in response when females have different levels of estrogens. These findings suggest that there are different pathways that are involved in learning and memory between the sexes and/or with different levels of estradiol. In this proposal, we plan to study how both factors (sex and estradiol) affect where and how learning and memory occurs in the brain. We will examine 1) activation of the hippocampus and other brain areas after memory, 2) how new brains cells respond to memory, and 3) whether the mechanisms in the brain cells driving memory are different in males and females, or females with different levels of estradiol. Understanding how biological sex and hormones can influence memory, may lead to a better understanding of how learning and memory is organized in the brain in both males and females, and ultimately of why some people are more susceptible to memory problems than others.