Figure 1.

Geometry and connectivity of a layered point-neuron network. (A) Schematic illustration of distance-dependent network connectivity using connectivity pattern tables (Nordlie and Plesser, 2010). Each row represents source populations X ∈ {STIM, EX, IN}, and each column target populations Y ∈ {EX, IN}. The color coding in each image shows the connection intensity between presynaptic neurons j and postsynaptic neurons i located in (x_j, y_j) and (x_i, y_i) with origin (0, 0) at the center. The connection intensities are defined as the product between pairwise connection probabilities ϵ_YX(r_ij) and synapse strengths g_YXJ for each respective connection. Gray values denote connection intensities of zero. (B) Illustration of one network instantiation with randomly drawn neuron positions and outgoing connections from a subset of neuronal units. The colored dots represent individual units at their (x, y)-coordinates. Gray dots denote units in a stimulus (STIM) layer, blue dots excitatory (EX) units, and red dots inhibitory (IN) units. Blue and red lines denote excitatory and inhibitory connections respectively, from a source unit (white circles) onto neurons within the same or another layer.