A Model for Grid Firing and Theta-Nested Gamma Oscillations in Layer 2 of the Medial Entorhinal Cortex
Grid cell circuits in the superficial layers of the medial entorhinal cortex have become a focus of considerable experimental and theoretical attention as a model for investigating neural mechanisms of cognition. Together, grid firing and associated theta-nested gamma oscillations can be considered as a minimal set of phenomena which a satisfactory model of superficial entorhinal circuits should account for. The model presented here focuses on stellate cells in layer 2 (L2SCs) and their indirect interactions through inhibitory interneurons. In the model, L2SCs and inhibitory interneurons are represented as distinct excitatory and inhibitory cell populations. To enable investigation of network activity patterns as well as network computations, the model is implemented using spiking exponential integrate and fire neurons. The model demonstrates that indirect interactions between L2SCs mediated via inhibitory neurons are sufficient for emergence of grid firing and nested game oscillations.