Temporal mapping in the human entorhinal cortex


Episodic memories are thought to be formed by binding events to their spatial as well as temporal context and medial temporal lobe structures have been implicated in the formation of such integrated memories. But which neural mechanisms allow us to remember when a specific event occurred? Theoretical accounts and recent empirical evidence suggest that the entorhinal cortex provides a slowly varying temporal signal, which might enable the tagging of individual events in time; thereby allowing the formation of a temporal mnemonic map. Here, we probe the development of temporal representations in the entorhinal cortex through learning. We relate changes in multi-voxel pattern similarity in entorhinal cortex to temporal distances between events participants encountered through repeated navigation along a fixed route in a large-scale urban environment. FMRI data were acquired during isolated presentation of events in random order, indicating that the observed similarity structure reflects the reactivation of a learned temporal mnemonic map rather than time per se. Our findings speak to how the entorhinal cortex might provide temporal context information for episodic memory and elucidate the mechanisms underlying the mapping of time in the medial temporal lobe in general.

San Diego, CA, US