Estimating orientation in natural scenes: A spiking neural network model of the insect central complex
Fig 2
Specific cell to cell connections between populations.
(A) Matrix showing connections between EPG, PEN, Δ7 and R cells, following previously determined connectivity [22, 24, 25]. Blue and red indicate excitatory and inhibitory connections respectively. EPG → EPG (weight 0.02), EPG → PEN (weight 0.13), EPG → R (weight 0.01), EPG → Δ7 (weight 0.05), PEN → EPG (weight 0.14), R → EPG (weight -1.3), and Δ7 → EPG (weight -2.6). (B) R2 (top) and R4 (bottom) ring neuron receptive field centers arranged in hexagonal pattern over the visual scene. Cells are ordered such that their receptive fields are arranged from bottom left to the top right of the scene along rows. The cell at the end of each row is labeled. (C) Inhibitory connections between ring neurons. These connections decay with distance between field centers with random scaling to produce irregular inhibitory regions of the receptive fields (see S1 Fig). R4 → R4 (max weight 0.3) and R2 → R2 (max weight 0.3). Not shown R4 → EPG (initial random weight between 0 and -0.05), R2 → EPG (initial random weight between 0 and -0.05).