SPATIAL FUNCTIONS OF THE MEDIAL TEMPORAL LOBE

内侧颞叶结构是如何促进记忆的？找到这个问题的答案是神经科学研究的长期目标。神经解剖学、行为学和功能成像研究的最新发现为这些内侧颞叶结构中的两个潜在功能提供了新的见解，这两个结构是海马区周围皮质和海马旁皮质。这些发现表明，就像海马体结构一样，这些皮质内侧颞叶区域也可能对空间功能有重要贡献。为了解决这种可能性，建议的研究结合使用敏感的神经解剖学追踪技术和单位神经生理学技术来探索脑周围和海马旁皮质在空间功能的两个方面的作用：空间表征和空间记忆。顺行追踪技术将被用来确定由参与处理刺激位置的“背流”结构产生的海马区旁输入的区域和层流地形图。单单位生理学技术将被用来定义动物执行延迟匹配放置任务时，海马周和海马旁皮质神经元携带的空间和助记信息的种类。这些实验还将确定这些区域中位置选择性神经元的空间参照系。另一项单独的任务将用来研究海马区和海马区周围神经元在形成新的对空间信息的长期记忆中的作用。当猴子在一系列复杂的视觉“场景”中学习特定奖励目标的空间位置时，神经活动将被记录下来。分析将针对识别任何与学习这些新的、长期的位置-场景关联相关的神经活动的“调整”。由于对空间信息的记忆在人类情节(即事件)记忆中扮演着如此重要的角色，这些研究的发现也可能有助于在猴子的实验工作和基于人类大脑记忆的当前工作之间建立联系。

How do medial temporal lobe structures contribute to memory? Finding the answer to this question is a long-term goal of neuroscience research. Recent findings from neuroanatomical, behavioral and functional imaging studies have provided new insight into the potential functions of two of these medial temporal lobe structures, the perirhinal and parahippocampal cortices. These findings suggest that like the hippocampal formation, these cortical medial temporal lobe areas may also contribute importantly to spatial functions. To address this possibility, proposed research combines the use of sensitive neuroanatomical tracing techniques and single-unit neurophysiological techniques to explore the role of the perirhinal and parahippocampal cortices in two aspects of spatial function: spatial representation and spatial memory. Anterograde tracing techniques will be used to define the regional and laminar topography of parahippocampal inputs arising from "dorsal stream" structures involved in processing stimulus location. Single unit physiological techniques will be used to define the kinds of spatial and mnemonic information carried by neurons in the perirhinal and parahippocampal cortices as animals perform a delayed match to place task. These experiments will also define the spatial frame of reference of the place-selective neurons in these areas. A separate task will be used to examine the role of perirhinal and parahippocampal neurons in the formation of new long-term memories for spatial information. Neural activity will be recorded as monkeys learn the spatial locations of particular rewarded targets in the context of a set of complex visual "scenes". Analyses will be directed at identifying any "tuning" of neural activity associated with learning these new, long-term location-scene associations. Because memory for spatial information plays such a prominent role in human episodic (i.e. event) memory, findings from these studies may also serve to establish links between experimental work in monkeys and current work on the brain basis of memory in humans.