Figure 7.

Responses of a bimodal, visual-auditory DSC unit over the full range of primary input levels. The responses were determined after the network containing this unit was trained using the two-stage algorithm with the following parameters: p_s = 0.34, p_c = 0.17, p_x0 = 0.1, p_x1 = 0.6,θ_u = 0.4, p_y0 = 0, p_y1 = 0.1,θ_x = 6,θ_y = 0, andθ_z = 0.2. The solid and dashed curves show the visual and auditory modality-specific responses, respectively. The curves with × symbols show the cross-modal response, and the curves with + symbols show the sum of the modality-specific responses. Responses with and without modulatory connections are shown in A and B, respectively. Responses at all input levels are subadditive without modulatory connections (B) but can be supra-additive over a narrow range with modulatory connections (A). V, Visual; A, auditory; S, somatosensory.