基于时域干涉效应的深部磁刺激系统设计OA

Transcranial magnetic stimulation(TMS)is a non-invasive bio-stimulation technique that is widely used in the clinical treatment of mental disorders such as depression and anxiety,as well as in neuroscience research.The study of deep neural modulation mechanisms is critical for treating mental illnesses and exploring their underlying causes.However,traditional TMS systems are effective at stimulating depths of 1.5 cm to 2 cm below the scalp,enabling cortical excitability regulation.It is difficult to produce an induced electric field that exceeds the neuronal excitation threshold in deeper brain regions,ranging from 4 cm to 8 cm below the scalp.In order to improve the deep stimulation effect of TMS,a deep magnetic stimulation system(DMSS)based on temporally interfering effect is proposed in this paper. Firstly,the interferential electric fields were introduced to the deep intracranial target area using the DMSS spatial array.The array contains four coils that are placed perpendicularly to the horizontal plane and tangentially to the scalp,constituting two sets of differential frequency stimulation pairs.Then,the DMSS stimulation circuit was designed to stably output two high-frequency pulsed stimulation currents to the spatial array.Next,the finite element numerical analysis was used to obtain the temporal and spatial distributions of the intracranial electric fields generated by the DMSS spatial array.Results showed that DMSS could generate a low-frequency electric fields in the deep region that was easy for neurons to respond dynamically,strengthen the deep stimulation,weaken the shallow stimulation,and produce an obvious focusing zone at the deep target area of 6 cm below the scalp.Under the same stimulation conditions,compared with the traditional TMS system,the DMSS can improve the intracranial longitudinal attenuation rate by a factor of 2.5,increase the stimulation depth by more than 4cm.Finally,the DMSS experimental platform was built and the system performance was tested to verify the feasibility of this design.The stimulating effects of DMSS were measured through a small detection coil with stimulation current frequencies of 5 000 Hz and 4 800 Hz.The electric fields in the deep region exhibited a low-frequency envelope with a frequency of 200 Hz.The electric fields intensity at the deep stimulation points was higher than that at the shallow stimulation points,which was consistent with the theoretical waveform shape. Combining the temporally interference effect with TMS design to improve deep brain stimulation performance is a highly promising research direction with vast application prospects in neuroscience and biomedical engineering.The distribution of electromagnetic fields is closely related to the geometric dimensions of electromagnetic field generating components.In this paper,the experimental platform was built with existing electronic components in the laboratory to verify the feasibility of the design at a low parameter level.In the next stage of research work,the parameter level of the experimental platform will be further improved and the peak value of the stimulation current will be increased to kiloampere level for animal experiment verification.