Fig. 2

Neuronal network bursting. Percentage of spontaneously active neurons in mapped neuronal networks at a DIV 9 and b DIV 16. A neuron was considered active when it exhibited >1% Ca responses (Δ F/F). A network bursting event was defined to occur when ≥20% of mapped neurons were active within the same 1-sec time frame. The bursting parameter, b, characterized the fraction of the time a neuron participated in a network bursting event. c 〈b〉 _avg , which is the average of b over all mapped neurons and over all networks for that day, shows network bursting as a function of network age