SPATIAL FUNCTIONS OF THE MEDIAL TEMPORAL LOBE

内侧颞叶结构如何影响记忆？找到这个问题的答案是神经科学研究的一个长期目标。最近来自神经解剖学、行为学和功能成像研究的发现为这两个内侧颞叶结构——周围皮层和海马体旁皮层的潜在功能提供了新的见解。这些发现表明，与海马体的形成一样，这些皮层内侧颞叶区域也可能对空间功能起重要作用。为了解决这种可能性，拟议的研究结合使用敏感的神经解剖学追踪技术和单单元神经生理学技术来探索周围皮层和海马体旁皮层在空间功能方面的作用：空间表征和空间记忆。顺行追踪技术将用于定义海马旁输入的区域和层流地形，这些输入来自参与处理刺激定位的“背流”结构。单单元生理学技术将用于定义动物在执行延迟匹配放置任务时，由周围皮层和海马旁皮层的神经元携带的空间和记忆信息的种类。这些实验还将定义这些区域的位置选择神经元的空间参考框架。另一项单独的任务将用于检查周围和海马体旁神经元在形成新的空间信息长期记忆中的作用。当猴子在一组复杂的视觉“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。分析将指向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“调谐”。由于空间信息记忆在人类情景（即事件）记忆中起着如此重要的作用，这些研究的发现也可能有助于在猴子的实验工作与当前人类记忆的大脑基础工作之间建立联系。

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.