We examine the effects of applied electric fields on neuronal synchronization. Two-compartment model neurons were synaptically coupled and embedded within a resistive array, thus allowing the neurons to interact both chemically and electrically. In addition, an external electric field was imposed on the array. The effects of this field were found to be nontrivial, giving rise to domains of synchrony and asynchrony as a function of the heterogeneity among the neurons. A simple phase oscillator reduction was successful in qualitatively reproducing these domains. The findings form several readily testable experimental predictions, and the model can be extended to a larger scale in which the effects of electric fields on seizure activity may be simulated.

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Previous experimental and simulation results have shown that potassium lateral diffusion can generate mutual interaction between neurons resulting in synchronization. The coupling mediator is extracellular potassium concentration. This concentration is modulated by the size of interstitial space. Yet the effect of extracellular space (ECS) size on the level of synchronization between neurons has not yet been studied. We hypothesize that the neuronal synchronization can be modulated by the size of ECS. To test this hypothesis, a two-cell model embedded in a 3compartment diffusion system was used. Each neuron was surrounded by interstitial space and immersed in the potassium bath. The simulation results show that as the ECS size decreases, synchronous states between non-identical neurons become asynchronous. Since a reduction of ECS size can be achieved by intensive neuronal activity such as epileptiform activity, the results suggest a possible mechanism for the development of synchronization in the process of sustained neuronal activity generated by potassium lateral diffusion. uptake pump glial buffer d J J J dt J J − −