Two- and three-neuron structural motifs in associative networks. A, Map of the overexpression ratios for bidirectional excitatory 2-neuron motifs shows no significant deviation from 1 in the entire range of the considered rescaled robustness and relative memory load. B, Normalized z scores of 16 3-neuron motifs in excitatory subnetworks indicate overexpression and underexpression of these structures compared with the chance levels. Red and green curves indicate the results for the parameter settings specified by the red and green asterisks in A. Error bars indicate SDs. C, Average fraction of excitatory 3-neuron motifs 6, 7, 13, and 14 appearing in associative networks among the top four z score motifs. Isocontour line, indicating the region of reasonably good solutions, is drawn as a guide to the eye. Results were generated based on 100 networks of N = 800 neurons.