Generation of population activities such as hippocampal sharp wave ripples and epileptiform discharges follows an emergent dynamics. During my postdoc with Richard Miles, we discovered that population discharges are initiated at a threshold firing level after recovery from a previous event (de la Prida et al., Neuron 2016). Each population discharge follows an active buildup period when synaptic recruitment and cell activity increase to threshold levels. Firing of densely connected individual hub cells can advance the onset of population events by increasing firing explosively. With these observations, we proposed a theoretical framework to understand the emergence of other population events such as sharp-wave ripples.