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Fig. 14.1. Self-organized vs. isotropic lateral connections. In (a), self-organized inhibitory lateral connection weights for a sample neuron in the LISSOM orientation map are plotted in gray scale from white to black (low to high); the small white square marks the neuron itself. In (b), the connections of a sample neuron in the network with isotropic long-range connections are shown. This network was constructed by adding two isotropic Gaussians: The smaller Gaussian was chosen as wide as the central peak in the self-organized weights, and the larger to extend as far as the longest self-organized lateral connections. Therefore, all neurons that are connected in the self-organized network are also connected in the sum-of-Gaussians network.