SPATIAL FIRING PROPERTIES OF HIPPOCAMPAL NEURONS

老鼠从不同的起点走直线的能力 不同的目标表明，他们的大脑中含有 在复杂的导航任务中使用的“认知地图”（43，72）。的 位置细胞的显著放电特性-仅当大鼠 是在其环境的一个特定部分-表明他们是一部分 认知地图的一部分。两条证据表明海马体 是老鼠导航的关键结构第一，海马锥体 神经元是定位细胞（45），第二，海马结构的损伤 使导航行为效率极低（34，65，51）。我们过去的工作 使用基于计算机的数据收集和简化技术来描述 单个位置细胞（40）的放电特性，并分析 环境操作对位置细胞活性的影响（36，37，39，）。 这里提出的工作扩展到更广泛的位置细胞的分析 contexts.拟议工作中最重要的方法变化 将是一组单独神经元的同步记录。这是 这是一种强大的技术，可以直接分析神经元活动 可能与其他神经元的活动有关，也可能与感觉或 行为变量 海马体的一个共同功能是决定 环境背景。事实上，人们经常认为， 在海马损伤的人中看到的缺陷是由于 上下文检索（13，78）。海马定位细胞 在几种环境下可以有明显独立的表现， 表明这些环境代表了背景。最广泛的 一项拟议的研究是从多个神经元中记录 环境.拟议研究与以往工作的差异 在于我们计划同时记录大量的神经元， 我们计划在更广泛的环境中记录这些集。 我们希望能够深入了解环境（上下文）的本质。 表示. 已经提出海马的表示是“地图样的”， 这意味着表示存储关于空间的信息， 环境中的区域关系。我们将测试这个想法， 在模糊刺激中同时记录神经元组 看看射击场是否保持其空间 相互尊重的关系。如果他们这样做，我们将得出结论， 表示具有“内聚”或“类似地图”的性质。 最后，我们将研究海马体在导航中的作用。 行为直接。地点单元格将在活动导航期间被记录 看看它们是否发出信号， 隐藏的目标 我们还将继续调查一只老鼠 海马受损时的导航能力。

The ability of rats to take straight paths from a variety of start locations to a variety of goals suggests that their brains contain "cognitive maps" that are used in complex navigational tasks (43,72). The remarkable firing property of place cells - rapid firing only when the rat is in a particular part of its environment - suggests that they are part of the cognitive map. Two lines of evidence suggest that the hippocampus is a critical structure in rat navigation. First, hippocampal pyramidal neurons are place cells (45), and second, damage to hippocampal structures makes navigation behavior highly inefficient (34,65,51). Our past work has used computer-based data collection and reduction techniques to describe the firing properties of individual place cells (40), and to analyze the effects of environmental manipulations on place-cell activity (36,37,39,). The work proposed here extends the analysis of place cells into broader contexts. The most significant methodological change in the proposed work will be simultaneous recordings from sets of individual neurons. This is a powerful technique that permits direct analysis of how neuronal activity can be related to the activity of other neurons, as well as to sensory or behavioral variables. One common function suggested for the hippocampus is to determine environmental context. Indeed, it is frequently suggested that the memory deficits seen in humans with hippocampal lesions are due to a defect in contextual retrieval (13,78). The finding that the hippocampal place cells can have apparently independent representations for several environments, suggests that these environments represent contexts. The most extensive proposed study is to record from sets of neurons across multiple environments. The differences between the proposed study and previous work lie in our plan to record from large sets of neurons simultaneously and our plan to record these sets over a much broader range of environments. We hope to gain insight into the nature of environmental (contextual) representation. It has been proposed that the hippocampal representation is "map-like", meaning that the representation stores information about the spatial relationships among regions in the environment. We will test this idea by recording simultaneously from sets of neurons in ambiguous stimulus situations to see whether the firing fields maintain their spatial relationships with respect to each other. If they do, we will conclude that the representation has "cohesive" or "map-like" qualities. Finally, we will investigate the role of the hippocampus in navigational behavior directly. Place cells will be recorded during active navigation to see whether they signal the rat's perception of the location of the hidden goal. We will also continue investigations into a rat's navigational abilities when the hippocampus is lesioned.