The Research Of Brain Voltage’s Frequency Change Characteristics Under Flash Stimulation

Brain voltage is the sum of potential on brain’s scalp generated by a large number of neurons’electrical activity. The level of activity and functional status of the nervous system can be reflected by brain voltage’s variation characteristics. In recent years, brain voltage become a hot topic at home and abroad because of its high temporal resolution, low cost and non-invasive security features. Due to the complexity and specificity of the nervous system, all kinds of factors that affect the brain voltage variation and its impact mechanism is committed to addressing the problem. This paper has studied the brain voltage’s frequency variation characteristic under flash stimulus at different flicker frequency, and explore the related mechanism, provide meaningful theoretical and experimental basis for people to better study brain voltage and its application. The main research is as follows.First, based on the mechanism of flash signal’s transduction, transformation and processing, and Hodgkin-Huxley circuit model, the neuronal current and membrane potential under different electrical stimulation were simulated. The relationship of changes in the frequency between flash stimulus and the neuronal periodic current was qualitative analyzed. The results showed that in a certain range, the neuronal current increases with increasing of the flash frequency, then tends to a steady value when the flash frequency exceeds a threshold.Second, according to antenna radiation theory, the brain voltage calculation model based on a small current ring equivalent to neurons was built. Combined with the amplitude-frequency characteristics of neuronal periodic current loop, the relationship of changes in the frequency between neuronal and brain voltage current was qualitative analyzed using the computational models. The results showed that each frequency component’s amplitude of brain voltage exists and is proportional to the frequency of neuronal current.Third, experimental study of the variation law of brain voltage frequency variation characteristic under flash stimulus at different flicker frequency was done. The results showed that, for flash stimulation of different frequencies, the variation law of brain voltage’s frequency characteristics is different, the power spectral density of brain voltage’s each component was inverted U-shaped nonlinear relationship with flash frequency:within a certain range, the power spectral density of brain voltage’s each component is proportional to the flash’s frequency. Once over this range, the power spectral density of brain voltage’s each component is inversely proportional to the flash’s frequency, decreasing with the flash’s frequency increasing.Last, the simulation results of changes relationship between flash stimulation and nerve current was analyzed. Combined with the brain voltage’s calculation model based on neurons current, the mechanism of the variation law of brain voltage frequency variation characteristic under flash stimulus at different flicker frequency was discussed, providing a meaningful experimental and theoretical basis for further exploring the response characteristics of nervous system to the outer stimulation.