Muller R U, Stead M
Department of Physiology, State University of New York-Brooklyn 11203, USA.
Hippocampus. 1996;6(6):709-19. doi: 10.1002/(SICI)1098-1063(1996)6:6<709::AID-HIPO13>3.0.CO;2-4.
We propose that a cognitive map can be stored in the synapses between the pyramidal cells of CA3 in the form of the pattern of synaptic strengths connecting them. The model requires only that there are place cells in CA3 and that the connections between them are modifiable in a Hebbian manner. Given these suppositions, the synaptic strengths must evolve to represent the distance between firing centers of synaptically connected place cells. We argue that this arrangement of synaptic weights embodies all the formal properties of a map. We demonstrate that the information stored in such a structure is sufficient to solve several classic spatial problems including finding shortest paths, and negotiating detours. It is clear that much of the physiology and anatomy necessary to more precisely characterize the model is not known at this time. Nevertheless the model is robust under a variety of cell and connection densities. It also performs well under several different functions relating distance to synaptic strength. What is most remarkable in the model is that it is a logical consequence of the several key anatomical and physiological properties of the CA3 region of rats. Whether this information is used by the rat is difficult to assess at this time. Regardless of the outcome of this question, the model has promising applications to the field of robot navigation.
我们提出，认知地图可以以连接CA3区锥体细胞的突触强度模式的形式存储在这些细胞之间的突触中。该模型仅要求CA3区存在位置细胞，且它们之间的连接能够以赫布方式进行修改。基于这些假设，突触强度必须不断演变，以表征突触连接的位置细胞放电中心之间的距离。我们认为，这种突触权重的排列体现了地图的所有形式属性。我们证明，存储在这种结构中的信息足以解决几个经典的空间问题，包括找到最短路径和避开弯路。显然，目前对于更精确描述该模型所需的许多生理学和解剖学知识尚不清楚。然而，该模型在各种细胞和连接密度下都很稳健。它在几种将距离与突触强度相关联的不同函数下也表现良好。该模型最显著的地方在于，它是大鼠CA3区几个关键解剖学和生理学特性的逻辑结果。目前很难评估大鼠是否利用了这些信息。无论这个问题的答案如何，该模型在机器人导航领域都有很有前景的应用。
