Figure 4: Simulation of theta phase precession in grid cell model based on membrane potential oscillations. (a) Theta phase plotted on vertical axis as a simulated rat runs through a grid cell firing field in west to east and east to west directions. (b) Theta phase during run from south to north. (c) Spike times (filled circles) of summed oscillations in a neuron relative to oscillation in the soma of that neuron (negative of network theta oscillation).