Modeling And Closed-loop Control Of Abnormal Rhythm In Cortical Network

Alzheimer’s disease is one of the neurological diseases with memory and cognitive decline.Many researches have found electrical stimulation could modulate abnormal rhythm in Alzheimer’s disease through electrical stimulation.In this thesis,a cortical network model was built to analyze the possible mechanism resulting in abnormal theta rhythm based on physiological phenomenon of abnormal rhythm in Alzheimer’s disease.The modulation mechanism of brain rhythm by electrical stimulation remains unclear,thus this thesis explores the modulation mechanism of brain rhythm by electrical stimulation and designs a closed-loop electrical stimulation control system.Firstly,a cortical network model is built based on the mechanism of the transformation from alpha to theta rhythm in Alzheimer’s disease.The effects of the inhibitory strength,excitation-inhibition ratio and the population size on the generation of the abnormal theta rhythm are analyzed.The results show that decreased inhibitory strength results in the abnormal theta rhythm.The decrease of excitation-inhibition ratio generates abnormal Alzheimer’s disease Alzheimer’s diseaseheta rhythm while the variation of the population size has no effect on the generation of the abnormal theta rhythm.Secondly,the cortical network response mechanism of electrical stimulation is analyzed when the model is subjected to electrical stimulation.Under different stimulus frequencies,the cortical network shows different response types.The response types show strong frequency dependence to stimulus frequency.Increased stimulus amplitude enhances the responses.Different stimulus waveforms generate different response types.The network responds as resonance,entrainment and non-linear acceleration under single anode pulse stimulation.While the network responds as resonance,entrainment and oscillation supression under biphasic pulse stimulation.Finally,PID-type iterative learning control is used to modulate and control the abnormal theta rhythm based on the cortical modle under electrical stimulation.Under different initial conditions and theta rhythm,the effective modulation and control of abnormal theta rhythm is implemented,which provides a new perspective for personalized therapy treatment.In summary,this thesis proposes a cortical network model of Alzheimer’s disease based on the phenomenon of the abnormal theta rhythm and the mechanism of the generation abnormal theta rhythm is analyzed.Closed-loop control method is adopted to regulate and control the abnormal theta rhythm.This provides enlightenment significance for the diagnosis and clinical treatment of Alzheimer’s disease.