| Low frequency (<1Hz) synchronized transitions between two levels of polarization have been observed in a variety of system. It is thought that both synaptic activity and intrinsic currents are responsible for this phenomenon. Instead of postulating the presence of a specific set of currents we consider networks of neurons of the integrate-and-fire type extended with a nonlinear intrinsic property. The model produces spontaneous transitions between up and down states. The transition from the down to the up is initiated by synaptic excitation and the cycle is terminated by synaptic inhibition. The model generates responses to sensory stimulation that depend on the state of the network at the time of the application of the stimulus. |
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