Neuronal connectivity schematic.

<p>Excitatory connections are represented with arrows and inhibitory connections with circles. Just two glomeruli are modelled, which are the convergent sites for axons of two ORN types (cyan for ORN1 and light green for ORN2). The receptor neurons provide afferent excitation to both classes of AL neurons. PNs, being exclusively uniglomerular, receive excitation from just one type of receptor, while LNs, being multiglomerular, receive excitation from multiple receptor types. LNs and PNs have mutual random connections (red and black solid lines – see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029602#s2" target="_blank">Methods</a>). PNs innervating a single glomerulus form random excitatory interconnections with fixed probability (dashed lines – see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029602#s2" target="_blank">Methods</a>). Two cases of inhibitory LN interconnectivity are considered: random connections of fixed probability to produce LCA behaviour (as in the example shown here) and all-to-all connectivity generating FPA behaviour (not shown).