Randomly connected white-noise network connectivity does not yield lognormal distribution of spontaneous firing rates. A, Synaptic connectivity matrix for 200 neurons. Because synaptic strengths are uncorrelated, the weight matrix looks like a white-noise matrix. B, Distribution of synaptic strengths is lognormal. The matrix is rescaled to yield a unit principal eigenvalue. C, Synaptic weights and firing rates of 12 randomly chosen neurons tended to be similar. Every circle corresponds to a single neuron, with diameter proportional to the spontaneous firing rate of the neuron. Thickness of connecting lines is proportional to strengths (synaptic weights) of incoming connections for each neuron. Red and blue circles and lines show spontaneous firing rates and incoming connection strengths for two neurons with maximum and minimum firing rates from the sample shown. Because incoming synaptic weights are similar on average, the spontaneous firing rates (circle diameters) tend to be similar. D, Spontaneous firing rates given by the components of principal eigenvector of matrix shown in A. The distribution of spontaneous firing rates is not lognormal, contrary to experimental findings (see A,B). The spontaneous firing rates are approximately the same for all neurons in the network.