fMRI of the Medial Temporal Lobe Memory System

内侧颞叶记忆系统的功能磁共振成像

• 批准号: 0236431
• 负责人: Craig Stark
• 金额: $ 55.95万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0236431&HistoricalAwards=false
• 关键词: fMRI; Medial; Temporal; Lobe; Memory

FMRI of Medial Temporal Lobe Memory SystemAbstract With National Science Foundation support, Dr. Stark will conduct a three-year study using eight functional magnetic resonance imaging (fMRI) experiments are proposed to explore the contributions to declarative memory that are made by the hippocampal region (the hippocampus proper, dentate gyrus, and subiculum) and the entorhinal, perirhinal, and parahippocampal cortices. The project is divided into three sub-projects, with each aimed at addressing a specific set of questions. In the first subproject, the relationship between the neural substrates for encoding and retrieval is investigated. The experiments here attempt to determine whether incidental, automatic encoding can be observed during a recognition memory task. These experiments make use of the finding that the level of activity during an intentional encoding task can predict participants' subsequent memory (Brewer et al., 1998; Wagner et al., 1998). Experiments 1 and 2 assess whether activity associated with the novel foil items during a recognition memory task can predict whether participants will be able to remember those items when a second recognition memory task is administered outside the scanner. The observation of encoding-related activity during memory retrieval would help explain several null results in the literature, including several recent studies that demonstrated activity in the hippocampal region under some conditions, but not others. The second sub-project (Experiments 3-5) asks whether the hippocampus is particularly involved in declarative memory tasks that require the formation and use of associations. Several variations of this hypothesis are represented strongly in the literature, but the current data are inconclusive as to whether an associative / non-associative distinction adequately captures the division between the role of the hippocampal region and the role of the adjacent cortical structures. Experiment 3 uses the Remember / Know procedure to explore this hypothesis. Experiment 4 is an fMRI version of a continuous recognition memory task that has been previously used to explore single-item and associative memory in amnesic patients. Finally, Experiment 5 seeks to determine whether medial temporal lobe activity during retrieval is affected by the number of associations that constitute a memory. In the third sub-project, the neural substrates of false memories are explored, with the hypothesis that understanding how memories fail, and understanding how true and false memories might differ, will further our understanding of how the declarative memory system operates. Experiment 6 is an fMRI extension of a recent ERP study of reality monitoring errors (misattributing a memory as originating from a real rather than an imagined event). Experiments 7a and 7b use a "misinformation" paradigm also to study distortions of memory source. Here, we propose to trace the activity associated with a memory from its original encoding, through the encoding of subsequent contradictory misinformation, and to relate activity at both stages to the likelihood of retrieval of either the original or the subsequent misinformation. These studies will help address a central issue in the field: whether misinformation impairs or interferes with the actual memory of the original event, or whether it has no effect on the memory for the original event. Using fMRI to address questions about the medial temporal lobe poses an array of significant challenges. Signals are noisy and weak, there is significant distortion due to magnetic field inhomogeneity, simple techniques to anatomically normalize participants often perform poorly, and the medial temporal lobe often appears to be active, despite our best attempts to make it otherwise. However, the techniques in the proposed projects are specifically designed to alleviate these concerns and to make fMRI of declarative memory in the medial temporal lobes more viable. By focusing on the medial temporal lobes, scanning parameters, alignment techniques, baseline tasks, and other aspects of experimental design can be tuned to optimize the quality of the data, and therefore the impact of the results.

斯塔克博士将使用八年的功能性磁共振成像（fMRI）实验进行三年的研究，以探索海马区域（海马适当，齿状gyrus and pareir the Enthinal and perimalhinal and Perorhinal and perirhinal and perimalhinal and perirhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and Perorhinal and prominal and Perorhinal and perirhinal and prom，皮层。 该项目分为三个子项目，每个项目旨在解决一组特定的问题。在第一个子项目中，研究了用于编码和检索的神经底物之间的关系。这里的实验试图确定在识别记忆任务中是否可以观察到偶然的，自动编码。这些实验利用了以下发现，即有意编码任务期间的活动水平可以预测参与者的后续记忆（Brewer等，1998； Wagner等，1998）。实验1和2评估在识别记忆任务期间与新型箔项目相关的活动是否可以预测参与者在扫描仪外进行第二次识别记忆任务时是否能够记住这些项目。在记忆检索过程中观察到与编码相关的活性的观察将有助于解释文献中的几个无效结果，其中包括最近在某些条件下显示海马地区活性的几项研究，但没有其他研究。第二个子项目（实验3-5）询问海马是否特别参与需要形成和使用关联的声明记忆任务。该假设的几种变体在文献中有很强的代表，但是目前的数据对于关联 /非缔合性区别是否充分捕获了海马区域的作用与邻近皮质结构的作用之间的分裂。实验3使用记住 /知道的程序来探讨这一假设。实验4是持续识别记忆任务的功能磁共振成像版本，该任务以前曾被用来探索失忆症患者的单个项目和联想记忆。最后，实验5旨在确定检索过程中内侧颞叶活性是否受构成记忆的关联数量的影响。 在第三个子项目中，探索了错误记忆的神经基础，这是理解记忆如何失败的假设，并且了解真实和错误的记忆可能会有所不同），将进一步了解我们对声明性记忆系统如何运作的理解。实验6是对现实监测错误最近的ERP研究的fMRI扩展（将记忆误导为源自真实事件而不是想象中的事件）。实验7a和7b使用“错误信息”范式还研究记忆源的扭曲。在这里，我们建议通过编码随后的矛盾错误信息来追踪与记忆相关的活动，并将两个阶段的活动与检索原始或后续错误信息的可能性相关联。这些研究将有助于解决该领域中的一个核心问题：错误信息是否会损害或干扰原始事件的实际记忆，或者它对原始事件的内存没有影响。 使用fMRI解决有关内侧颞叶的问题提出了一系列重大挑战。信号嘈杂且虚弱，由于磁场不均匀性而存在明显的失真，简单的技术在解剖学上使参与者的表现往往很差，并且内侧颞叶通常似乎是活跃的，尽管我们尝试了否则它的最佳尝试。但是，拟议项目中的技术是专门设计的，可以减轻这些关注点，并使内侧颞叶中声明性记忆的fMRI更加可行。通过关注内侧颞叶，可以调整扫描参数，对准技术，基线任务和实验设计的其他方面，以优化数据的质量，从而优化结果的影响。