压后皮质在空间导航的作用：认知地图与环境的映射

压后皮质在大脑中紧邻胼胝体压部，在空间导航中起到重要作用。但其在空间导航过程中的功能尚未明确，目前存在空间更新、地标领航和参照系转换三种观点。本文通过梳理上述观点，认为它们背后可能存在一致的认知过程，即对认知地图与环境布局进行映射。在基于认知地图的导航过程中，这种映射功能对于解释压后皮质的激活有一定的合理性。未来研究应该注重对压后皮质的功能定位，同时注意空间尺度和熟悉性对任务表现的影响。

The function of the Retrosplenial Cortex in Spatial Navigation: from Cognitive Map to Environment

Spatial navigation, an inherent wayfinding process that combines multiple cues to accurately pursue the destination, is considered as an important process referring to the survival and reproduction of humans and animals. For decades, researchers have devoted to studying the neural underpinnings of spatial navigation and detected several brain areas associating with navigation process, including the hippocampus, entorhinal cortex, and retrosplenial cortex (RSC). The present study focuses on summarizing the function of the RSC in spatial navigation. The RSC refers to the region in the posterior of the splenium of the corpus callosum and comprised of Brodmann’s Areas 23, 29, and 30. Although the engagement of the RSC in spatial navigation and memory formation has been revealed by many studies, there is no consensus as to its precise function in spatial cognition. Previous studies suggested that the function of the RSC in spatial navigation can be classified into three types, spatial updating, landmark piloting, and reference translation. Spatial updating refers to a dynamic cognitive process that accounts for perceiving changes in the environment during the navigation. The head-direction cells which fire when the animal faces a particular direction are thought to involve in the process of spatial updating. Landmark piloting refers to the use of landmarks to orientate and to trace the location of the destination. The main evidence comes from clinical studies that found patients with RSC impairment are hard to use landmarks to recall the map in their familiar environment. Reference translation means a mental process that keeps the spatial information available between reference frames. Animal experiments showed that rats with the RSC lesions were difficult to complete the navigation task requiring switching between multiple reference frames. In the present review, we describe a comprehensive perspective of the RSC function in spatial navigation: the mapping function of the RSC, which means that the RSC mapping the cognitive map to the environment to maintain a consistent layout between them. To prove the rationality of this mapping function, we list three possible reasons as follows: First, spatial updating, landmark piloting, and reference translation show somewhat overlapping with each other which indicates a common process underlying these functions. Second, the graph-like organization of cognitive map indicates a flexible layout during its formation. The graph-like cognitive map gives the topological relationship of objects, but lack of geographic information like sizes, angles, and distances. Therefore, the cognitive map should be mapped to the environment to afford enough spatial details in further navigational decisions. Third, the roles of the RSC on the cognitive map may be similar with the remapping process of the hippocampus. In the future study, it would better (1) using the localizer task to locate the RSC in individual-level, (2) exploring the dynamic properties of the RSC activation by specific experimental design to improve the ecological validity, and (3) understanding the subfield function of the RSC and its functional connectivity with other brain regions.