Implementing Entorhinal Grid Fields in Biophysical Neuronal Models

The responses of rat medial entorhinal cortical neurons form characteristic grid patterns as a function of the animal’s position. A recent model of grid fields proposes a mechanism based on intrinsic single cell properties. It relies on interference patterns emerging from multiple distinct and independent oscillations maintained in the dendritic tree of the cell. Here we examine the requirements necessary to implement this idealized mechanism in a biophysically realistic model. We find that appropriate grid field-formation by a single cell is exquisitely sensitive to intra-dendritic interactions. Mathematical analysis shows how these effects depend on properties of the dendritic oscillators and the (active) membrane segments that connect them. This work gives explicit requirements for a single cell implementation of grid-field activity.