Different dendritic sectors could interfere one with each other in determining complex BPR combinations and sequences (Santamaria and Bower, 2005). The interference was determined by the generation of non-linear supra-threshold events driven by Ca spikes. Threshold crossing depended on a minimal number of active synapses and was enhanced by the high input conductance of terminal regions. As an important consequence, this would make the aa superior to pf synapses for generating dendritic Ca spikes and in controlling dendritic response patterns (Bower, 2002).