A model of the endogenous electrical field effect: Can ephaptic transmission cause neuronal synchronization independently?

An endogenous electrical field effect, i.e., ephaptic transmission, occurs when an electric field associated with activity occurring in one neuron polarizes the membrane of another neuron. It is well established that field effects occur during pathological conditions, such as epilepsy, but less clear if they play a functional role in the healthy brain. Most of studies put excessive attention on the mechanism of chemical synapse. However, the mechanism of ephaptic transmission is still uncertain. Recently, some physiologic studies speculate that ephaptic transmission can cause neuronal synchronization, such as in teleost Mauthner cells. But this conclusion is not well verified. Here, a model is set up to study the effect of ephasptic transmission to neuronal synchronization independently without any other interactive ways. The role of neuronal heterogeneity to endogenous electrical field effect is also investigated. The simulation results showed that 1) Ephaptic transmission can be responsible for independently inducing neuronal synchronization and the network shows higher synchronicity when the coupling strength increasing; 2) In sufficiently heterogeneous ensembles, increasing coupling strength tends to desynchronize the network.