<p>Illustration of the additive process used to generate connectivity.</p>

Black circles are drawn at radius and around the highlighted neuron A for reference. <b>(B)</b> The adjacency matrix scaffold for this illustration, drawn pseudorandomly from a uniform distribution. Darker squares will be connected at lower probability thresholds . <b>(C)</b> The resulting adjacency matrices for two values each of and .

Neuron pairs that are too distant (i.e., their distance is greater than ) are disconnected, along with the diagonal (i.e., no autapses), as illustrated by the red hatching. Neuron pairs that are within the spatial window for , but whose value of exceeds , are disconnected and shown hatched in grey (same color scale as in panel <b>B)</b>. Neuron pairs that meet the criteria for both distance () and probability () are connected and shown in solid color, with different hues indicating connections that are present throughout (blue), added by increasing (green), increasing (orange), or increasing both and together (red). <b>(D-E)</b> Adjacency matrices of one network “prototype” (see text).