Mechanism Of Modulation Of Neural System With Electric Fields

Transcranial electromagnetic stimulation is a noninvasive method widely used in the study of cognitive function and various neural physiological diseases as well as the treatment of pain disorders.However,the underlying mechanism of these methods modulating neural activities is unclear,causing a lack of perfect protocol standards to guide and standardize the technology which seriously restrict the development of the technology.All of these electromagnetic stimulation modalities stimulate the neurons in the target area by inducing an electric field in the extracellular space of brain and cause polarization in neurons.It is found that the effect of electromagnetic field stimulation on nervous system is a result of the combination of internal and external electric field.Endogenous field,evoked by structured neuronal network activity in vivo,is correlated with many vital neuronal processes.Therefore,the study of internal and external electric field is of vital significance in understanding the underlaying mechanism of electromagnetic stimulation on neuron activities.According to the extracellular mechanism,set up a hippocampal area CA1 pyramidal neuron model under the stimulation of uniform electric field.The response characteristics of neuron to electric stimulation and the effects of basic morphological parameters on the neural response to the extracellular uniform electrical field stimulation is analyzed and studied.It is found that morphological factors can nonlinearly affect the neuronal response of the extracellular electrical field and different segments of neuron have a different sensitivity to the extracellular uniform electric field stimulation.In addition,the relative position of neuron and electric field is also an important factor to influence field effect.Furthermore,it is found that the existence of excitatory postsynaptic potential makes the neuron easier to discharge and electric field stimulation threshold decreases with the increase of its amplitude.It also can modulate the impact of morphological factors.A neural network model with endogenous field feedback and feedback delay is established.The phenomenon of stochastic resonance in neural network is studied.We systematically analyzed the modulation effect of endogenous field on stochastic resonance in neural networks.It is found that there exists an optimal endogenous field feedback coefficient making the stochastic resonance of the nervous system to achieve the best performance.It is also revealed that appropriately tuned delays of the feedback can either induce the improvement of weak signal detection ability of neuron network,appearing at every integer multiple of the weak input signal's oscillation period,or the destruction of it,appearing at every integer multiple of half the weak input signal's oscillation period.The study in this paper study the modulation effect of electric field stimulation on neural activities from the point view of endogenous and exogenous electric field and the results obtained have great importance in revealing the underlie mechanism of how neuron encodes electric field stimulus and finding the optimal stimulus amplitude.