Figure 1. The entorhinal grid system as coupled 2D continuous attractor networks (Materials and methods).

(A) Each network z corresponds to a region along the dorso-ventral MEC axis and contains a 2D sheet of neurons with positions (x,y). (B) Neurons receive excitatory drive a(x,y) that is greatest at the network center and decays toward the edges. (C) Neurons inhibit neighbors within the same network with a weight w(x,y;z) that peaks at a distance of l(z) neurons, which increases as a function of z. Each neuron has its inhibitory outputs shifted slightly in one of four preferred network directions and receives slightly more drive when the animal moves along its preferred spatial direction. (D) Each neuron at position (x,y) in network z excites neurons located within a spread d of (x,y) in network z – 1.