Entorhinal cortical grid cells fire in a periodic pattern that tiles space, which is suggestive of a spatial coordinate system. However, irregularities in the grid pattern as well as responses of grid cells in contexts other than spatial navigation have presented a challenge to existing models of entorhinal function. In this Perspective, we propose that hippocampal input provides a key informative drive to the grid network in both spatial and non-spatial circumstances, particularly around salient events. We build on previous models in which neural activity propagates through the entorhinal–hippocampal network in time. This temporal contiguity in network activity points to temporal order as a necessary characteristic of representations generated by the hippocampal formation. We advocate that interactions in the entorhinal–hippocampal loop build a topological representation that is rooted in the temporal order of experience. In this way, the structure of grid cell firing supports a learned topology rather than a rigid coordinate frame that is bound to measurements of the physical world.

内嗅皮层网格细胞以周期性模式放电，平铺空间，这暗示了空间坐标系。然而，网格图案的不规则性以及网格细胞在空间导航以外的环境中的响应对现有的内嗅功能模型提出了挑战。在本视角中，我们提出海马输入在空间和非空间环境中为网格网络提供关键的信息驱动，特别是在显着事件周围。我们建立在以前的模型的基础上，其中神经活动通过内嗅-海马网络及时传播。网络活动中的这种时间连续性表明时间顺序是海马结构生成的表征的必要特征。我们主张内嗅-海马环路中的相互作用建立了一种植根于经验时间顺序的拓扑表征。通过这种方式，网格单元发射的结构支持学习的拓扑，而不是绑定到物理世界的测量的刚性坐标系。