Control of Declarative Memory Processing in the Medial Temporal Lobe

描述(由Candiate提供)：拟议研究的广泛目标是调查内侧颞叶(MIL)回路中的陈述性记忆过程如何受到认知目标的调节，这些目标使加工偏向于学习或提取信息。实验一将使用高分辨率功能磁共振成像(FMRI)来测试在编码过程中表现出新颖性效应(对新刺激比对旧刺激更活跃)的MIL亚区在情景提取过程中是否也表现出回忆效应(对记住的旧刺激比对新刺激更活跃)。这样的发现将支持MIL功能的概念化，即感觉刺激的MTL加工不是由它们的助记历史决定的，而是由一个人在遭遇时的助记目标决定的。实验2将使用高分辨率功能磁共振成像来评估是否存在MIL皮质区--通常显示出对先前遇到的新刺激的反应减弱--可以颠倒这种反应模式，并积极地帮助回忆与先前刺激遭遇相关的感觉细节。鉴于大脑周围皮质和海马旁皮质有不同的感觉输入，在情景回忆过程中这些区域的参与被预测为关键取决于正在被回忆的是基于物体的信息还是基于空间的信息。实验3将假设，根据记忆目标调节MTL区域的反应轮廓的能力依赖于前额叶皮质的控制机制。此外，顶叶后皮质被认为是为了监控从MTL发出的助记信号，或者引导人们注意被提取的记忆的内部代表内容。实验3将使用全脑功能磁共振成像和功能连接分析来研究前额叶和顶叶区域如何与MTL相互作用，以促进新奇编码和情景回忆。描绘MTL反应受到自上而下控制信号影响的方式将推进对陈述性记忆的机械性解释，并为当PFC和/或MTL功能受到精神分裂症、注意缺陷多动障碍、抑郁、衰老或痴呆影响时助记控制过程如何崩溃提供深入的见解。相关性：这项研究将使用功能磁共振成像来检查我们的行为目标如何影响感觉信息的神经处理，从而促进新的学习或从长期记忆中检索相关细节。表征这些控制过程如何影响内侧颞叶的特定机制，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.