Analysis And Control Of Initial Dynamical Mechanism For Neural Action Potential

Acupuncture is an important part of Chinese medicine with unique ways ofthinking and rich experiences whose efficacy has been proved by Chinese clinicalresearch during thousands of years. The same manual acupuncture applied to differentacupoints will exert distinct influence. The exact mechanism of this difference is stillunclear at present. Transcranial magnetic stimulation (TMS) and Transcranialelectrical stimulation (TDCS) are effective methods for the treatment of neurologicaldiseases. However, the identical action will yield different effect in differentindividual. Nervous system achieves information transmission and reception bycoding externally-applied stimulation. The inherent mechanism of different effectsproduced by the same stimulus is due to the diversity of firing initial dynamicalmechanisms. Therefore, this paper puts forward the following hypothesis:acupuncture and TMS affect neural coding by changing the firing initial dynamic.Taking action potential initiation dynamical mechanisms as the breakthrough point,the influence of acupuncture and TMS are equivalent to electric current and electricfield stimulation respectively in this paper. Then, neuron model under stimulation isset up and used to study the impact mechanism by which stimulus parameters andneuron intrinsic channel properties exert influence on the neural coding. To realize thecontrol of neural coding, bifurcation control and closed-loop control methods areemployed. The results in this thesis give some theoretical supports to the research ofacupuncture neuron coding and the action mechanism of TMS.(1) To the better understand neural coding in acupuncture, this paper study theimpact mechanism by which stimulus parameters and neuron intrinsic channelproperties exert influence on the threshold value of firing. Then a threshold equationof neuron firing is established through the equivalent between acupuncture andelectric stimulus for the first time. In addition, three different value regions of ionicconductance corresponding to the three types of excitabilities are distinguished whichproves that the types of neuron’s excitability are determined by the shape ofsubthreshold ion current activation curve.(2) A minimum neuron model under the external electric field induced by TMS isbuilt for the study of mechanism by which TMS exerts influence on neural coding.Various neural firing patterns under alternating current electric field are analyzed. Thedynamical mechanism of externally-applied electric field is researched by phase plane analysis and bifurcation analysis method. Through this research, it’s found thatexternally-applied electric field can change competition results between the ioncurrents with different dynamics under the threshold of potential, leading to threedifferent firing patterns.(3) Considering the relationship between subthreshold current of neuron and theaction potential initiation dynamical mechanism, a dynamic control method usingWash-out filter is proposed. The transform between different neuronal excitability isachieved by this method. Through this research, it’s found that Wash-out filterchanges the position of Hopf bifurcation point by affecting the competition resultbetween subthreshold ion currents.(4) Close-loop electrophysiology experiment is the effective method to realizethe change of neural coding, by which neural coding can be changed arbitrarily. Toreduce the influence of uncertainty and noise in the neuron model, closed-loopelectrophysiology experiment method is put forward. Choosing the stochastic HHsingle compartment model and multi compartment mode as the controlled object, theabnormal firing initiation and the transmission of firing are controlled by adaptivefuzzy control method. The results show noise generates abnormal code by affectingthe stability of neuronal equilibrium point.(5) For the closed-loop electrophysiology experiment control of demyelinationneuron and the difficulties in the measurement of neuronal internal state, the paper isthe first study of close-loop state feedback tracking control method based on Kalmanfilter estimation. This method forces the demyelination neuron to tracking the normalsingle spike and restrains propagation of abnormal coding mode along axon. Theresearch finds that the change of ion conductivity leading to the appearance of Hopfbifurcation is the dynamic basis of abnormal coding. In addition, it shows that theoutput current of this control method is within the physiological current that can bebear by neuron, that is to say, this method can be used in the closed-loopelectrophysiology experiment control.