Control of Declarative Memory Processing in the Medial Temporal Lobe

描述（由候选人提供）：拟议研究的广泛目标是调查内侧颞叶（MIL）回路内的陈述性记忆过程如何受到认知目标的调节，这些目标使处理偏向于学习或信息检索。实验1将使用高分辨率功能性MRI（fMRI）来测试在编码过程中表现出新奇效应（对新刺激比旧刺激更活跃）的MIL子区域在情景提取过程中是否也表现出回忆效应（对记住的旧刺激比新刺激更活跃）。这样的发现将支持MIL功能的概念化，其中MTL对感觉刺激的处理不是由它们的记忆历史决定的，而是由一个人在遇到时的记忆目标决定的。实验2将使用高分辨率的功能磁共振成像来评估是否有情况下，MIL皮层区域-这通常表现出减少反应，以前遇到相对于新的刺激-可以反转这种反应模式，并积极促进与以前的刺激遇到的感官细节的回忆。鉴于不同的感觉输入到嗅周和海马旁皮质，这些区域的参与在情节回忆预测关键取决于是否基于对象或基于空间的信息正在回忆。实验3将承担的假设，即根据记忆的目标，调制MTL区域的响应曲线的能力取决于控制机制subserved由前额叶皮层。此外，后顶叶皮层被假设为监测来自MTL的记忆信号或将注意力引导到检索记忆的内部表征内容。实验三将使用全脑功能磁共振成像和功能连接分析，以探讨如何前额叶和顶叶区域与MTL相互作用，以促进新奇的编码和情景回忆。描述MTL反应受自上而下控制信号影响的方式将推进陈述性记忆的机制解释，并提供对当PFC和/或MTL功能受到精神分裂症、注意力缺陷多动障碍、抑郁症、衰老或痴呆症损害时记忆控制过程如何崩溃的见解。相关性：这项研究将使用功能性MRI来研究我们的行为目标如何影响感官信息的神经处理，以促进新的学习或从长期记忆中检索相关细节。描述这些控制过程如何影响内侧颞叶内的特定机制，将有助于我们更好地了解影响这些结构的临床条件下记忆障碍的性质，如精神分裂症，抑郁症和痴呆症。

DESCRIPTION (provided by candidate): The broad aim of the proposed research is to investigate how declarative memory processes within the medial temporal lobe (MIL) circuit are modulated by cognitive goals that bias processing toward the learning or the retrieval of information. Experiment 1 will use high-resolution functional MRI (fMRI) to test whether the MIL subregions that show novelty effects (greater activity to new vs. old stimuli) during encoding also exhibit recollection effects (greater activity to remembered old stimuli vs. new stimuli) during episodic retrieval. Such a finding would support a conceptualization of MIL function in which MTL processing of sensory stimuli is not dictated by their mnemonic history, but rather by one's mnemonic goals at the time of encounter. Experiment 2 will use high-resolution fMRI to assess whether there are circumstances in which MIL cortical regions-which typically show a diminished response to previously encountered relative to novel stimuli-can invert this response pattern and actively contribute to the recollection of sensory details associated with prior stimulus encounters. Given the distinct sensory inputs to the perirhinal and parahippocampal cortices, the engagement of these regions during episodic recollection is predicted to depend critically on the whether object-based or spatially-based information is being recollected. Experiment 3 will bear on the hypothesis that the ability to modulate the response profile of MTL regions in accordance with mnemonic goals depends on control mechanisms subserved by prefrontal cortex. Moreover, posterior parietal cortex is hypothesized to monitor mnemonic signals emerging from MTL or to direct attention to the internally-represented contents of retrieved memories. Experiment 3 will use whole-brain fMRI and functional connectivity analyses to examine how prefrontal and parietal regions interact with MTL to facilitate novelty encoding and episodic recollection. Delineating the manner in which MTL responses are influenced by top- down control signals will advance mechanistic accounts of declarative memory and provide insights into how mnemonic control processes break down when PFC and/or MTL function is compromised by schizophrenia, attention-deficit hyperactivity disorder, depression, aging, or dementia. Relevance: This research will use functional MRI to examine how our behavioral goals influence the neural processing of sensory information, serving either to promote new learning or the retrieval of relevant details from long-term memory. Characterizing how these control processes influence specific mechanisms within the medial temporal lobes will help us better understand the nature of memory impairments in clinical conditions that affect these structures, such as schizophrenia, depression, and dementia.