Study On TDCS Simulation And Optimization System Based On Real Head Model

With the development of non-invasive brain stimulation(NIBS)technology,transcranial direct current stimulation(t DCS),a seemingly simple stimulus,is being widely used in various situations,including neurological disorders,neurological rehabilitation and cognitive enhancement.It has been reported that t DCS has a certain effect on improving various forms of learning in humans.t DCS has obvious advantages in inducing synaptic plasticity,the role of anodic stimulation in the regulation of neuronal cell excitability and the inhibition of caterpillar stimulation on neuronal cells has been revealed as a stimulation mechanism of transcranial current stimulation(t CS).However,due to the action of t DCS,the complex electric field distribution in the brain is induced,and the parameters of the electrodes,the electrode configuration,and the difference in the structure of the human brain also make the stimulation results very different,which is also an important factor affecting the accuracy of the stimulus.Based on the purpose of realizing the targeted stimulation of t DCS and improving the accuracy of stimulation,this thesis firstly investigated the electric field distribution characteristics of each electrode configuration by establishing a real head model,and combined with the research results,the whole brain electrode configuration optimization was performed,and it is desirable to obtain a better stimulation electrode combination and injection current intensity under the condition of stimulating the target brain region.In order to accomplish this aim,this study carried out the following works:First of all,based on the high-resolution magnetic resonance imaging(MRI)data,our study explored a universal method for constructing a head model.By studying various current segmentation algorithms and modeling methods,Gaussian mixture was used to divide the head organization structure,and then the Simpleware software was used to construct the solid model and the finite element meshing process,Finally,a real head model closer to the human tissue structure was reconstructed.Based on this,the foundation of the electric field simulation is completed.After the construction of the head model,according to the electrode configuration appearing in previous studies,this study separately arranged conventional rectangular electrodes,4×1 dot electrodes,ring electrodes,and double ring electrodes with different shapes on the surface of the head model,explored the electrode shape’s influence on inducing intracranial electric field distribution.It was found that the traditional rectangular electrode could induce the strongest electric field strength of the grey matter cortex under the condition of consistent injection current,but the focusing and stimulating permeability were relatively low in the region of interest(ROI).In contrast,the 4×1 dot electrode,the ring electrode and the double ring electrode had better focusing performance and higher tissue permeability.In addition,in the study of the influence of the distance between the cathode and the anode on the intracranial electric field distribution,the 4×1 dot electrode was selected to explore the electric field difference between the cathode and anode distances in range of 1 to 5 cm.The results showed that with the increase of the distance between the cathode and the anode,the maximum electric field strength induced in the grey cortex gradually increases,and the maximum field strength could be controlled within the electrode coverage,but when the cathode-anode distance increased to more than 4 cm,the electrode gradually lost the ability to control the location of the stimulus.And under the 4×1 dot electrode,the distance of the electrode had little effect on the permeability of the tissue.In addition,the process of achieving targeted stimulation in patients with schizophrenia was investigated,taking the t DCS processing in patients with schizophrenia as an example.To solve the problem of applying optimal stimulation to the bilateral dorsolateral prefrontal cortex(DLPFC)in schizophrenia patients,the 10-10 system-oriented electrode in the EEG system was selected under the basic conclusion of the possible effects of electrode characteristics on brain current progression.For the target brain regions,the target of making the activation stimulus on the left ROI and suppressing stimulation on the right ROI was constructed.Moreover,constraints on the injection current of a single electrode and the brain region outside the target area was imposed,and perform constrained optimization solution to achieve the forward current stimulation for the left DLPFC and the maximum negative stimulus for the right DLPFC.In conclusion,to certain current,this study preliminary obtaining better stimulation in the target area,which is likely to guide a better electric field and bring safe and convenient treatment to patients with schizophrenia.