Research On The Model Of Electric Field Effects And Dynamic Mechanisms Of The Hippocampus Pyramidal Neuron

As a typical neural system disease, epilepsy is characterized by oversynchronousfiring induced by the hyperexcitability of neurons in neuronal populations. Externallyapplied electromagnetic field stimulation has been an effective way to suppressepileptic seizures. However, geometry characteristic of the neuron is related to theelectromagnetic field modulation on neuronal activities. Hippocampus is believed tobe an important area of epileptic generation and seizure, and the individual pyramidalcells are aligned such that adjacent cells have parallel dendrites, which favorinteraction with fields aligned along the collective soma-to-dendritic axes. Therefore,the electric field effects model of hippocampal pyramidal neuron is developed withthe electrical characteristics of extracellular medium and mechanisms of electric fieldeffect on neuronal activities under ephaptic transmission are studied in the work. Thestudy may be potentially helpful in development and application of electromagneticstimulation technique for the treatment of epilepsy.Combine the conductive characteristics of extracellular medium and thehippocampal slice experiments in the presence of electric field, the electric fieldeffects model of the neuron is constructed and validated. Based on the field effectsmode, the modulation of neuronal electric activities is studied both in direct-current(DC) and alternating current (AC) fields.It is found that the negative field could excite the neuron back into spikingbehavior in high strength. The interesting phenomenon coincides with the result inhippocampal slices experiment. It is explained in mechanism in the work.The neuron is sensitive to the frequency and amplitude of AC electric field. Theneuron exhibits various firing patterns, including different phase locking patterns,chaos and transition states with different frequencies and amplitudes of the electricfield. Furthermore, the extracellular resistance can modulate the efficacy of electricfield effects ephaptically.Based on the field effect model of the hippocampal pyramidal neuron, appliedsubthreshold electric field, stochastic resonance is studied in noise environment. The optimum noise values are found to help the transduction of the subthreshold electric.In this case stochastic resonance is generated and the subthreshold electric field effecthas been amplified.In the paper, under the ephaptic transmission field effects on pyramidal neuronfiring activities are investigated both in DC and AC electric fields. The result could besignificant to reveal the mechanisms of environmental electromagnetic field effects onneuron and also be contributed for the treatment of epilepsy with the electromagneticstimulation technique.