Hippocampal Representation of Sequential Information

这个项目将研究海马体内的神经元集合，以及相关的 海马旁皮质区和前额叶皮质，代表信息服务的情节 非空间信息的记忆。我们的实验是由这样一个假设指导的： 单个项目和空间背景分别表示在不同的海马旁区域，该区域 CAS在它们所经历的环境中对项目进行编码，并且该区域CA 1编码和检索 体验物品的顺序;我们的实验以哈塞尔莫的模型为指导 这一机制的基础。多通道微电极将用于记录放电模式 海马，海马旁和前额区神经元的神经元， 这些任务评估了老鼠记忆一次呈现的气味序列的能力， 消除重叠气味序列的歧义。在序列记忆范式中，我们将描述和 在这个大脑系统中定位序列编码、空间背景编码和项目熟悉性编码。在 序列消歧范例，我们将测试假设，重叠事件在两个 对于每个序列，序列被不同地表示。在这两种范式中，我们将确定 存在发生序列信息的编码和检索的θ节律的特定阶段， 以及来自最近经历的顺序信息是否在记忆延迟期间持续。所有 这些措施，我们将表征神经放电模式预测记忆性能的程度。 这些研究的设计和重点是由对人类行为的观察指导的。 类似的任务，并提供了细胞水平的分析，不可能在人体功能成像研究。 这些实验将与空间序列加工的平行研究进行比较，以确定非空间序列和空间序列的共同基本机制 表示.实验的目的是检验模型，指导进一步的开发 海马电路模型支持情节记忆的时间组织。

This project will examine how neuronal ensembles within the hippocampus, as well as associated parahippocampal cortical areas and prefrontal cortex, represent information in the service of episodic memory for non-spatial information. Our experiments are guided by the hypothesis that information about individual items and spatial context are separately represented in distinct parahippocampal areas, that area CAS encodes items in the context in which they were experienced, and that area CA1 encodes and retrieves the order in which the items were experienced; and our experiments are guided by Hasselmo's models of the mechanisms underlying this scheme. Multi-channel microelectrodes will be used to record the firing patterns of neurons in hippocampal, parahippocampal, and prefrontal areas in rats performing hippocampaldependent tasks that assess rats' ability to remember once-presented sequences of odors and to disambiguate overlapping odor sequences. In the sequence memory paradigm, we will characterize and localize sequence coding, spatial context coding, and coding of item familiarity within this brain system. In the sequence disambiguation paradigm, we will test the hypothesis that overlapping events in two sequences are represented distinctly for each sequence. In both paradigms, we will determine whether there are specific phases of the theta rhythm on which encoding and retrieval of sequence information occur, and whether sequential information from recent experiences persists during a memory delay. For all of these measures we will characterize the extent to which neural firing patterns predict memory performance. The design and focus of these studies is guided by observations of humans performing similar tasks and provides a cellular level analysis not possible in functional imaging studies on humans. These experiments proposed here will be compared with parallel studies on spatial sequence processing, seeking to identify common fundamental mechanisms of non-spatial and spatial sequence representation. The experiments are aimed to test models and to guide the further development of models of hippocampal circuitry that support the temporal organization of episodic memory.