Fig. 1. The general structure of the network in neonatal (fig. 1A) and in mature (fig. 1B – 1C) phase.

The four projection areas make excitatory synapses with their target interneurons (arrows). In the neonatal configuration (fig. 1A) only non-AEV and non-FAES input regions are connected with their target SC neurons and their correlated interneurons are effective; on the contrary, projections from AES subregions are not mature and their interneurons haven’t influence on the SC activity. In the adult configuration (fig. 1B) all the four unisensory input areas send excitatory synapses to the SC and the four interneuron populations are effective. These interneurons provide two competitive mechanisms: 1) Ha and Hv provide the bases through which the inhibitory effect of AES is imposed on non-AES inputs; 2) Ia and Iv provide the substrate for a competition between two non-AES inputs in which the stronger one overwhelms the weaker. In panel C, a schematic picture of the network is reported to highlight the more important parameters of the model.