Fig. 1.

Two-level neural network. The lower level comprises monocular left and right eye neurons selective for orthogonal gratings, represented here as vertical and horizontal hatching. Monocular neurons representing different eyes and grating orientations are mutually inhibitory, represented by heavy lines with filled circles at the ends (for clarity, inhibitory interneurons are not shown). The second model stage represents higher-level binocular neurons that receive stimulation (arrows) from left and right monocular neurons with the same preferred grating orientation. These higher-level neurons also engage in competitive inhibitory interactions, again represented by the heavy line terminating with filled circles. Recurrent excitation, when implemented (see text), was represented by feedback from each binocular neuron to both of its monocular inputs.