Sparse bursting model predictions: A: burst duration (top), spikes per burst (middle), and sparseness (bottom) as a function of gGABAA. Solid lines: mean. Dashed lines: mean ± SD. At gGABAA ≥ 0.4 mS/cm2, the burst duration is 5.0 ± 0.3 ms and the number of spikes per burst is 3.6 ± 0.1. B and C: HVCI interspike interval (ISI) distributions may differentiate between connectivity patterns. B, top: ISI distribution of HVCI neurons in the simulation shown in Fig. 4B, connected according to the rule described herein. Bottom: ISI distribution of HVCI neurons receiving completely random synapses from the same set of HVCRA neurons. C: the same ISI distributions, with lower y-axis and higher x-axis limits. Top: ISI distribution of HVCI neurons connected according to the rule described herein shows a characteristic dip. Bottom: ISI distribution of HVCI neurons receiving random synapses lacks this dip.