Threshold effects in dendritic sectors. In these simulations on the Z+ PC model, type II BPRs were elicited by 500 Hz—10 spikes pf bursts in dendritic sectors II and SC synapses were activated by 130 Hz—three spikes trains in the same sector. The number of active pf synapse was increased from 50 to 100. Traces on the left show membrane potential in a compartment of sector II. The dendritic response remained sub-threshold until around 70 synapses and then jumped steeply over-threshold generating Ca spike at 80 synapses. The plot on the right shows the amplitude of the dendritic depolarization as a function of the number of activated synapses.