Fig 1. Firing rates without compensation in model cortices of various sizes.

A. Mean firing rates of Excitatory (red) and Inhibitory (blue) neurons in the optimal patch in response to a vertical grating at high contrast. Firing rates for the full-size cortex are shown, as are those for the 1/2, 1/4, ⋯, 1/49-cortices using identical synaptic weights as the full-size cortex. Five trials (different networks with different initial conditions) were run for each cortex size. Each trial was run for 7 sec, and the open circles denote the E and I-firing rates averaged over the last 5 sec. All trials had converged long before the end of the 7 sec except for one of the trials for the 1/4-cortex (red and blue squares). Results across trials for each cortex size were consistent except in the case of the 1/4-cortex, which had two limiting values; the 1/9-cortex also showed greater variations than others. B. The two graphs show optimal (solid) and orthogonal (dashed) firing rates of E neurons in the models. Optimal and orthogonal firing rates were far apart in the full-size and 1/2-cortices, suggesting orientation selectivity. OS was lost for the 1/4- and smaller cortices. All other trials showed similar results with regard to OS.