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Fig. 3.6. Self-organization of a retinotopic map. For each neuron in the network, the center of gravity of its weight vector is plotted as a point on the receptor surface. Each point is connected to the centers of the four neighboring neurons by a line (note that these connections only illustrate neighborhood relations between neurons, not actual physical connections through which activity is propagated). Initially the weights are random, and the centers are clustered in the middle of the receptor surface. As self-organization progresses, the points spread out from the center and organize into a smooth topographic map of the input space.