Simulation And Experimental Study Of Transcranial Magnetic-acoustical Electrical Stimulation Based On Realistic Human Head Model

Transcranial magnetic-acoustical electrical stimulation(TMAES)is a new type of non-invasive brain modulation technology,which uses ultrasonic waves and static magnetic fields to act on neural tissues to modulate neuronal firing activity.TMAES is of great significance for the research and treatment of brain functional diseases.At present,there are many research of TMAES stay at the neuron level,but few on the macro-focusing effect.Therefore,the relevant research was carried out in this article.The main contents are as follows:1.The CT image data of the human head was utilized to construct a realistic human head model by using medical image processing methods.And the realistic human head model was optimized to make it advantageous for finite element simulation calculation.Then meshed the realistic human head model to generate a finite element head model that can be used for simulation analysis.2.The finite element analysis software Comsol was utilized to simulate the distribution of induced current density during TMAES.The distribution of ultrasound field and induced current density were obtained by simulation.The results showed that there was a high consistency between them.TMAES formed a spindle-shaped focal spot in the human brain.The intensity of the stimulation was sufficient to make a suprathreshold stimulation of neurons.The spatial-peak temporal-average intensity over the focal point did not exceed the ultrasonic safety threshold specified by the America Food and Drug Administration.Theoretical analysis and experimental methods were used to verify the safety of TMAES.And the frequency of ultrasound was also considered whether it will affect the focusing performance of TMAES.Ultrasonic waves with frequencies of 300,400,and 500 k Hz were applied on the realistic human head model during TMAES.The results showed that the increase of the frequency of the ultrasonic signal will lead to the increase of the stimulation intensity,the stimulation length and the focus area.3.An experiment of TMAES in human was designed to verify its safety and effectiveness,the motor cortex of human was selected as the target area for stimulation.The experiment was divided into a control group and an experimental group.Sham stimulation and TMAES were applied to the two groups,and the EMG of the abductor pollicis brevis of the right arm of the participants were collected with the surface electrodes while applying the stimulation.According to whether the potential of the abductor pollicis brevis of the right arm exceeds 50 μV or whether thumb shaking can be observed to determine whether an effective stimulus is formed,the experimental results showed that the success rate of evoked action potential in the experimental group was 93.75%;and in the control group was 0.This confirmed the effectiveness and safety of TMAES.In summary,TMAES was discussesed from the perspective of theoretical analysis and experimental research.A realistic human head model was constructed and used,and the effects of acoustic non-uniformity was considered as well as the distribution difference of conductivity in different organizations.The modeling material was derived from real head data to ensure the reliability of simulation analysis.The experimental design was based on the safety of the participants.In order to respect human rights and comply with ethical standards,non-invasive surface electrodes was used to collect EMG signals.The safety and effectiveness of TMAES had been confirmed.This article provided theoretical guidance for TMAES,and also promoted the development of TMAES in clinical applications.