Probing interactions of working- and long-term memory

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。该奖项是NSF社会、行为和经济科学博士后研究奖学金（SPRF）计划的一部分。SPRF计划的目标是为学术界，工业或私营部门和政府的科学事业准备有前途的早期职业博士级科学家。SPRF的奖励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。NSF致力于促进来自科学界各部门的科学家，包括来自代表性不足的群体的科学家参与其研究计划和活动;博士后期间被认为是实现这一目标的专业发展的重要水平。每个博士后研究员必须解决推进各自学科领域的重要科学问题。在加州圣地亚哥大学的约翰·塞萨尔博士的赞助下，这个博士后奖学金支持了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。工作记忆是指在短期内将信息暂时保存在脑海中的能力。长期记忆是指在较长时间内（从瞬间到几十年）编码和检索信息的能力。研究人员煞费苦心地分别测量每种记忆，部分原因是它们天生倾向于合作（例如，在工作记忆中比较持有字母XZK-FGC-KZPW与DOG-CAT-BIRD）。为了在没有长期记忆支持的情况下估计工作记忆容量，实验室研究通常使用人为刺激（例如，任意颜色-位置配对）。这种还原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功能的理解。在日常生活中，要记住的项目很少没有意义，多个记忆系统串联使用（例如，当你在问答游戏中被要求按字母顺序列出披头士成员的名单时，你必须首先从长期记忆中提取信息，然后用工作记忆处理它。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，这项研究计划的目的是更好地了解这些规范可分离的记忆系统何时以及为什么相互作用。由于工作记忆和长期记忆在日常生活中交织在一起，认知可能会因为一个或两个结构的困难而失败。因此，这项基础科学工作也对理解正常衰老和临床人群中同时发生的工作记忆和长期记忆缺陷具有影响，以及对工作记忆和长期记忆如何在教育环境中协同工作的影响（例如，当学生遇到新的信息，他们必须保持在工作记忆中，然后再回忆）。基于几十年来对支持工作记忆和长期记忆的可分离神经机制的研究，该项目将使用功能磁共振成像来测试关于大脑皮层中活跃工作记忆维持信号相互作用的相互竞争的预测（即，解码记住的项目的身份）与来自长期记忆的支持的神经签名（即，海马激活）。前两个实验地址竞争帐户的容量限制，积极的，皮层工作记忆代码和海马活动如何支持WM时，这个容量限制被超过。剩下的两个实验解决了活动沉默工作记忆的竞争性账户-最近流行的想法，即皮层内的快速突触可塑性可以在没有持续活动的情况下支持工作记忆的维持。本项目研究另一种解释，即如果持续活动丧失，工作记忆行为可能依赖于活动代码的大脑皮层依赖性恢复。拟议中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竞争理论帐户提供信息。无论结果如何，这些发现都将为人类记忆的现有理论提供信息和扩展，并且在拟议工作中开发和完善的方法有可能为未来的问题提供信息（例如，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.