The Integrate and Fire (IF) neuron model wasusedto simulate ultra-slow oscillations that were observed in cortical cultures. Simulation of a network with 2 sub-networks is conducted in this study. We introduced an additional equation that governs the generation and dissipation of an inhibitory property to each of the sub-network.Sub-networks that fire at different rate are generated from the simulation. The network activity from the simulation oscillates at frequencies that are comparable to ultra-slow oscillations observed in cortical cultures.