Bi-estabilidade de fase em populações neuronais

Abstract

Synchronization of non-linear systems has been extensively studied in several systems both in physics and biology. In particular, an unusual type of synchronization, called anticipated synchronization (AS), was discovered by Voss, when two dynamic systems were unidirectionally coupled. The AS regime can occur when a dynamic system ("sender") described by a set of ordinary differential equations is coupled unidirectionally to a "receiver" system described by the same equations but subjected to a negative delayed self-feedback. In such cases, AS is characterized by a negative phase difference between the transmitter and the receiver. Recently it was reported that the electrical activity of cortical regions of the monkey brain can display this type of synchronization during the performance of cognitive and motor tasks. In this work, we studied a model of neuron populations of Izhikevich that can display both the AS regime and the usual delayed synchronization regime (DS), characterized by a positive phase difference. In this model each neuron receives an external noise, simulating excitatory synapses coming from other brain regions, which obey a Poisson distribution. We show that for a set of biologically plausible parameters, this model presents a bistable regime between DS and AS. We also found that the properties of this bistability depend on the relationship between the synaptic conductances of the receiving population, the unidirectional coupling, and the external noise in each neuron. We suggest that this motif could represent a toy model for cortical regions during bistable percepetion.