Modeling And Optimization Of Transcranial Electrical Stimulation Based On MRI Real Head Model

With the development of non-invasive brain stimulation techniques,transcranial Electric Stimulation(tES)has been favored by many researchers for its advantages of low cost,non-invasiveness,and high safety.However,due to the complex electric field distribution induced by tES stimulation,a systematic and comprehensive understanding of the distribution characteristics of the electric field in the brain under transcranial electric stimulation is crucial for optimizing stimulation effects and guiding stimulation protocol selection.Exploring the simulation of electric field distribution in transcranial electrical stimulation is based on reconstructing a more accurate realistic head model.This article used high-resolution(0.5mm)and highly versatile magnetic resonance data as the basis,and used Mimics software to construct a realistic head model that is closer to human tissue.Based on this,the article explores the distribution of intracranial electric fields through simulation.Using the COMSOL simulation platform,this study established three electrode models,including traditional patch electrodes,ring electrodes,and 4×1 high-definition electrodes,and conducted comparative analysis of the simulation effects.The results showed that the 4×1 high-definition electrode had higher focusing ability and less shunting effect,making it more favorable for focusing stimulation targets.However,the electric field intensity induced by the 4×1 electrode was smaller than that induced by the traditional patch electrode.To improve the electric field intensity induced by the 4×1 electrode,this study proposed a mixed current injection mode.Based on the 4×1 electrode,the study compared the electric stimulation effects of the mixed current injection mode with 1mA direct current and peak 1 mA frequency 10 Hz alternating current、1.5mA direct current and peak 0.5 mA frequency 10 Hz alternating current、0.5mA direct current and peak 1.5 mA frequency 10 Hz alternating current and the electric stimulation effect induced by 2 mA direct current(alternating current)alone.The results showed that the proposed mixed current injection mode induced an electric field intensity of 0.42 V/m in the gray matter cortex,which was significantly higher than the electric field intensity of 0.32 V/m induced by the 2 mA direct current alone.To further optimize the electric stimulation effect,this study introduced the algorithm of adding the λ term.Targeting the primary motor cortex as the target area for directional stimulation,the study used the algorithm of adding the λ term,as well as the least squares method,the maximum intensity method,and the constrained maximum intensity method proposed by previous researchers to obtain the optimal electrode combination and current injection intensity scheme for the target area.The results showed that the introduced algorithm of adding the λ term had significantly improved the maximum electric field intensity of 0.39 V/m and focusing ability of 8.4767 compared to the constrained maximum intensity method,which induced a maximum electric field intensity of 0.37 V/m and focusing ability of 7.1825.In summary,this study established a high-precision head model based on high-resolution and highly versatile MRI data,used the COMSOL simulation platform to conduct research on the optimal stimulation protocols for three electrode structures,including traditional patch electrodes,ring electrodes,and 4×1 high-definition electrodes.Through comparative analysis,the feasibility of two optimization schemes,mixed current injection mode and algorithm of adding the λ term,was verified,providing a model reference for the clinical application and scientific research of tES technology.