Probing interactions of working- and long-term memory

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。该奖项是作为NSF社会、行为和经济学博士后研究奖学金(SPRF)计划的一部分提供的。SPRF计划的目标是为学术界、工业界或私营部门和政府的科学职业生涯培养有前途的、早期职业博士水平的科学家。SPRF奖项包括在知名科学家的赞助下进行两年的培训，并鼓励博士后研究员进行独立研究。国家科学基金会致力于促进科学界所有阶层的科学家参与其研究方案和活动，包括那些来自代表性不足的群体的科学家；博士后阶段被认为是实现这一目标的专业发展的一个重要水平。每个博士后研究员都必须解决推动各自学科领域向前发展的重要科学问题。在加州大学圣地亚哥分校约翰·塞伦斯博士的赞助下，这一博士后奖学金奖项支持一位研究工作记忆和长期记忆相互作用的早期职业科学家。工作记忆指的是在短期内暂时记住信息的能力。长期记忆是指在较长时期(从瞬间到数十年)对信息进行编码和检索的能力。研究人员花了很大力气来分别测量每种记忆，部分原因是他们自然倾向于合作(例如，比较工作记忆中持有字母XZK-FGC-KZPW和狗-猫-鸟)。为了在没有长期记忆支持的情况下估计工作记忆容量，实验室研究经常使用人为的刺激(例如，任意的颜色位置配对)。这种简化论的方法揭示了工作记忆和长期记忆具有独特的行为特征，并依赖于可分离的神经机制。然而，这种方法扭曲了我们对工作记忆如何发挥作用的理解。在日常生活中，要记住的东西很少是没有意义的，而且会同时使用多种记忆系统(例如，当在琐事中被要求按字母顺序写出披头士成员名单时，你必须首先从长期记忆中检索信息，然后用工作记忆来处理它)。因此，工作记忆和长期记忆的相互作用对人类记忆至关重要，本研究计划的目的是更好地了解这些规范分离的记忆系统何时以及为什么相互作用。因为工作记忆和长期记忆在日常生活中是交织在一起的，认知可能会因为其中一个或两个结构上的困难而失败。因此，这项基础科学工作对于理解在正常衰老和临床人群中共同出现的工作记忆和长期记忆缺陷，以及对于教育环境中工作记忆和长期记忆如何协同工作(例如，当学生遇到他们必须在工作记忆中保存并随后回忆的新信息时)也有意义。基于对支持工作记忆和长期记忆的可分离神经机制的数十年研究，该项目将使用fMRI来测试关于大脑皮质中活跃的工作记忆维持信号相互作用的相互竞争的预测(即，对记忆中物品的身份进行解码)与来自长期记忆(即，海马体激活)的支持的神经特征相结合。前两个实验解决了活跃的皮质工作记忆代码的容量限制以及当超过这个容量限制时，海马体活动如何支持WM的相互竞争的描述。剩下的两个实验讨论了关于活动的相互竞争的描述--沉默的工作记忆--这是最近流行的一种想法，即在缺乏持续活动的情况下，皮质内的快速突触可塑性可以支持工作记忆的维持。这个项目调查了另一种解释，即如果失去持久活动，工作记忆行为可能依赖于海马体依赖的皮质活动代码的恢复。这项拟议的研究将利用功能磁共振成像和多变量建模来为工作记忆和长期记忆的相互竞争的理论解释提供信息。无论结果如何，这些发现都将告知并扩展现有的人类记忆理论，而在拟议工作中开发和改进的方法有可能为未来的问题提供信息(例如，对记忆文献中的其他开放问题进行解码的能力将对记忆文献中的其他开放问题有用)。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Under the sponsorship of Dr. John Serences at the University of California San Diego, this postdoctoral fellowship award supports an early career scientist investigating the interaction of working memory and long-term memory. Working memory refers to the ability to hold information temporarily in mind over the short term. Long-term memory refers to the ability to encode and retrieve information over longer periods (from moments to decades). Researchers have taken great pains to separately measure each kind of memory, in part because they naturally tend to cooperate (e.g., compare holding the letters XZK-FGC-KZPW vs. DOG-CAT-BIRD in working memory). To estimate working memory capacity without support from long-term memory, laboratory studies often use contrived stimuli (e.g., arbitrary color-location pairings). This reductionist approach has revealed that working- and long-term memory have unique behavioral signatures and rely on dissociable neural mechanisms. However, this approach skews our understanding of how working memory functions. In everyday life, to-be-remembered items are rarely devoid of meaning and multiple memory systems are used in tandem (e.g., when asked at trivia to write an alphabetical list of Beatles members, you must first retrieve the information from long-term memory and then manipulate it with working memory). Thus, the interaction of working- and long-term memory is critically important to human memory, and the objective of this research program is to better understand when and why these canonically dissociable memory systems interact. Because working- and long-term memory are intertwined in everyday life, cognition can fail due to difficulties with one or both constructs. Accordingly, this basic science work also has implications for understanding co-occurring working- and long-term memory deficits in normal aging and in clinical populations, as well as implications for how working- and long-term memory work in tandem in educational settings (e.g., when students encounter novel information they must hold in working memory and then later recall).Building on decades of research on the separable neural mechanisms that support working- and long-term memory, the project will use fMRI to test competing predictions about the interaction of active working memory maintenance signatures in cortex (i.e., decoding the identity of items held in mind) with neural signatures of support from long-term memory (i.e., hippocampal activation). The first two experiments address competing accounts of the capacity limits of active, cortical working memory codes and how hippocampal activity may support WM when this capacity limit is exceeded. The remaining two experiments address competing accounts of activity-silent working memory – a recently popularized idea that rapid synaptic plasticity within cortex can support working memory maintenance in the absence of persistent activity. This project investigates the alternative account that working memory behaviors may rely upon hippocampal-dependent cortical reinstatement of active codes if persistent activity is lost. The proposed research will leverage fMRI and multivariate modeling to inform competing theoretical accounts of working- and long-term memory. Regardless of the outcome, the findings will inform and extend existing theories of human memory, and the methods developed and refined in the proposed work have the potential to inform future questions (e.g., the ability to decode the identity 4 items held in mind would be useful for other open questions in the memory literature).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.