SPATIAL FIRING PROPERTIES OF HIPPOCAMPAL NEURONS

老鼠从各种不同的起点走直线的能力 不同目标的位置表明他们的大脑包含 用于复杂导航任务的“认知图”(43，72)。这个 Place细胞显著的放电特性--只有当大鼠 处于其环境的特定部分--表明它们是 认知地图上的。有两条证据表明，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，对海马体结构的损害 使导航行为非常低效(34，65，51)。我们过去的工作 使用基于计算机的数据收集和还原技术来描述 单个位置细胞(40)的放电特性，并分析 环境操纵对位置细胞活动的影响(36，37，39，)。 这里提出的工作将放置单元的分析扩展到更广泛的领域 上下文。拟议工作中最重大的方法变化 将是来自多组单个神经元的同时记录。这是 一种强大的技术，可以直接分析神经元的活动 可能与其他神经元的活动有关，也可能与感觉或 行为变量。 海马体的一个常见功能是确定 环境背景。事实上，人们经常认为，记忆 在患有海马区损害的人类中所见的缺陷是由于 上下文检索(13，78)。发现海马区的位置细胞 可以在多个环境中具有明显独立的表示， 表明这些环境代表上下文。最广泛的 拟议的研究是记录来自多个 环境。拟议的研究与以前工作之间的差异 在于我们的计划是同时从大量的神经元和 我们计划在更广泛的环境中记录这些场景。 我们希望深入了解环境(上下文)的本质 代表权。 有人提出，海马区的表征是“地图状”的， 这意味着该表示存储有关空间的信息 环境中各区域之间的关系。我们将通过以下方式测试这一想法 从模糊刺激中的多组神经元同时记录 情况，看看射击场是否保持其空间 相互尊重的关系。如果他们这样做了，我们将得出结论 这种表述具有“内聚性”或“地图状”的特点。 最后，我们将研究海马体在导航中的作用 直接的行为。在活动导航期间将记录放置单元格 来看看它们是否发出信号，让老鼠感觉到 隐藏的目标。我们还将继续调查一只老鼠的 当海马体受损时的航行能力。

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.