Figure 5.

Schematic of the association of grid to environment via phase reset of grid cells by place cells. Left: Diagram showing anatomical connection from mEC grid cell (pale blue) with three dendritec subunits (green, blue, red) to hippocampal place cell (gold) and feedback from place cell onto the dendrites of the grid cell. Center: the maximal firing of the place cell occurs in phase with theta (above, dashed line), and resets dendritic membrane potentials to be in phase with theta (below), Right: the path of the rat in the open field and the place cell's firing field (gold, above). In a familiar environment connections from the place cell to the grid cell are developed due to their coincident firing fields (right: above and middle). These connections enable maximal firing of the place cell to reset the phases of the grid cell's dendritic membrane potential oscillations (MPOs) to be in phase with theta – forcing the grid to stay locked to the place field at that location, by ensuring that the envelopes of the three dendritic linear interference patterns coincide at the location of the place field (below right). Sensory input from the environment (especially boundaries), via lateral entorhinal cortex (lEC), keeps the place field locked to the environment. For convenience, only one place cell and one grid cell are shown – in practice we would expect multiple grid cells (with firing at the place field) to project to the place cell, and multiple place cells (with coincident place fields) to project to the grid cell. See Figure 4 for details of the grid cell model.