Control of Declarative Memory Processing in the Medial Temporal Lobe

描述（由候选人提供）：本研究的主要目的是研究内侧颞叶（MIL）回路中的陈述性记忆过程是如何被认知目标调节的，这些认知目标会使记忆过程偏向于学习或信息检索。实验1将使用高分辨率功能性磁共振成像（fMRI）来测试在编码过程中表现出新颖性效应（对新刺激比旧刺激更活跃）的MIL亚区在情景检索过程中是否也表现出回忆效应（对记忆中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，即感觉刺激的MTL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（fMRI）来评估，在某些情况下，MIL皮质区域（通常对先前遇到的新刺激表现出较弱的反应）是否可以逆转这种反应模式，并积极促进与先前遇到的刺激相关的感觉细节的回忆。考虑到向周围皮层和海马体旁皮层的不同感觉输入，预测这些区域在情景回忆期间的参与主要取决于是基于物体的信息还是基于空间的信息被回忆。实验3的假设是，根据记忆目标调节MTL区域的反应谱的能力取决于前额叶皮层的控制机制。此外，后顶叶皮层被假设为监测来自颞叶颞叶的助记信号或将注意力引导到检索到的记忆的内部表征内容。实验3将使用全脑功能磁共振成像和功能连通性分析来检查前额叶和顶叶区域如何与MTL相互作用，以促进新颖性编码和情景回忆。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，并提供关于当PFC和/或MTL功能因精神分裂症、注意缺陷多动障碍、抑郁症、衰老或痴呆而受损时，助记控制过程如何中断的见解。相关性：本研究将使用功能性核磁共振检查我们的行为目标如何影响感觉信息的神经处理，以促进新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理解影响这些结构的临床条件下记忆障碍的本质，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.