Content representation in the human medial temporal lobe

描述（由申请人提供）：记忆功能的基本问题是信息如何在大脑中表示。目前的模型表明，我们经历的内容可能是由解剖学上不同的大脑结构来表征的，这些表征的性质可能会随着它们从新信息转变为存储的记忆而改变。虽然内侧颞叶（MTL）在情景记忆（个别事件的记忆）中的核心作用已经确立，但其内容表征的性质仍不清楚。MTL的解剖结构表明，每个MTL亚区对基于内容的情景记忆编码有独特的贡献。然而，这些区别的证据是混杂的。这项研究计划将结合高分辨率功能性磁共振成像（fMRI）和高维分析，以比以前更高的精度揭示MTL对内容敏感编码的分区域贡献。实验1将验证MTL皮层亚区和海马体对不同形式的内容作出独特反应以支持项目水平编码的假设。一种新的多变量分析技术将使我们能够评估阈下活动所携带的信息。它还将揭示内容表示在成功编码后的发展本质。实验2将检验特定类别的内容表征被恢复以支持情景细节记忆的假设。我们还将考虑海马体子区的反应，以确定它们在介导编码和恢复中的计算作用。实验3将检验内容表征被重新激活以帮助预测未来的假设。多元

DESCRIPTION (provided by applicant): The fundamental question underlying memory function is how information is represented in the brain. Current models suggest that the content of our experiences might be represented by anatomically distinct brain structures, and the nature of those representations might change as they are transformed from novel information to stored memories. Although the central role of the medial temporal lobe (MTL) in episodic memory-memory for individual events-is well established, the nature of content representation in the MTL is still unclear. The anatomical organization of the MTL suggests that individual MTL subregions make unique contributions to the encoding of episodic memories based on content. However, evidence for these distinctions has been mixed. This research proposal will combine high-resolution functional magnetic resonance imaging (fMRI) and high-dimensional analyses to reveal the MTL subregional contributions to content-sensitive encoding with greater precision than previously possible. Experiment 1 will test the hypothesis that MTL cortical subregions and hippocampus make unique responses to different forms of content to support item- level encoding. A novel multivariate analytical technique will allow us to assess the information carried by subthreshold activity. It will also reveal the developing nature of content representations as they are successfully encoded. Experiment 2 will test the hypothesis that specific categories of content representation are reinstated to support memory for episodic details. We will also consider the responses of hippocampal subfields to determine their computational role in mediating encoding and reinstatement. Experiment 3 will test the hypothesis that content representations are reactivated to help anticipate the future. Multivariate analysis of patterned activation during timepoints before expected events will test whether they carry information predicting the content of those events. This research will help identify the nature of content representation in the MTL, giving us a clearer picture of how we remember the world around us. It will also give us insight into the possible functional role of content codes in MTL. Understanding these open questions through the completion of the proposed project will help us identify the underlying nature of impairment from conditions that affect MTL function or structure, including Alzheimer's disease, post-traumatic stress disorder, and schizophrenia. )