A reversing buffer mechanism that enables instances of retrospective activity in hippocampal regions CA3 and CA1

We simulate temporal context dependent episodic memory with resulting reversed order activity in model hippocampal regions CA3 and CA1, similar to recorded activity recently published by D.J.Foster and M.A.Wilson. Our model supposes that encoding of reversed place associations in CA3 is the cause of that activity. That proposed mechanism is the focus of this paper, and we simulate resulting activity in model layer III of entorhinal cortex, and in hippocampal regions CA3 and CAI. Learning associates spike episodes maintained in a persistent firing buffer in layer II of entorhinal cortex (ECII) with unique temporal context specific representations formed in dentate gyrus (DG), as well as with episodic memory encoded in the CA3 recurrent network. Similarly, spiking representations in DG are associated with episodic memory in CA3. Spike sequences retrieved in CA3 are reversed representations of the original episodic input. As observed by Foster and Wilson, and in more recent electrophysiology, resulting simulated activity in CAI exhibits some forward and some reversed spiking.