Figure 4. Structure of neural field model.

We built a neural field model based on the established functional organization of primate early visual cortices to simulate how the scaling of intracortical circuits with visual cortical surface area influenced the perception of different visual features. We modelled the processing of four basic visual features—orientation, contrast, luminance and visual field location. (a) In accordance with the empirical literature, model neurons responded to contrast in monotonic function, and orientation, luminance or visual field location in Gaussian functions. (b) The orientation or visual field location preference of the model neurons was laid out in an orderly fashion where intracortical connectivity covaries with the similarity in feature preference between connected neurons; by contrast, the contrast or luminance preference of the model neurons was laid out in a randomized fashion without systematic relationships between intracortical connectivity and neural feature preference. As a result, for the processing of orientation or visual field location, the decrease of intracortical connectivity with increased visual cortical surface area predominantly influenced the connectivity between model neurons with similar feature preference, whereas for the processing of contrast or luminance the influence on the connectivity between model neurons with similar feature preference was counter-balanced by that between model neurons with opposite feature preference.