Development of an Extremely Low Frequency Magnetic Field Generator and Its Application in Nerve Cell Electrophysiological Characteristics Research
|School||Huazhong University of Science and Technology|
|Keywords||Neurons Hippocampus Patch clamp Ion channels Magnetic field Stochastic processes Wavelet Transform Autoregressive (AR) model|
Bioelectric activity is an important organism life activities. Neurons and patch-clamp electrophysiology study ion channels are two important areas. Bioelectric activity since it is an electric, they are bound by external electromagnetic activity to a certain extent influence. Currently used magnetic stimulation of nerve cells and tumor cells are two important biomagnetic research topics suitable magnetic stimulation of the nervous system diseases play a therapeutic role, such as Parkinson's disease, neuropathic pain, epilepsy, depression, schizophrenia psychosis, the hippocampus is important for learning and memory brain regions, especially in the important areas of disease Parkinson's disease. This article uses a magnetic field to stimulate hippocampal cells discharge signals through the nerves and potassium ion channel signal analysis to study the electrophysiological properties changes. The study has important theoretical significance and practical value. Firstly, the design of a magnetic stimulation electrophysiological experiments generic ELF magnetic field generator, the instrument can produce a variety of waveforms, frequency, intensity and spatial distribution of the magnetic field. Then through the patch-clamp neurons and two methods of ion channels in rat hippocampal cells before and after effects of ELF magnetic fields and ion channel properties and discharge characteristics were studied. Final analysis of two interrelated methods the results. This research work is mainly research results obtained are as follows: (1) developed a bio-magnetic stimulation for multiple waveforms, multi-parameter magnetic field generator. The instrument is characterized by: a) Power from several milli-tesla (mT) up to 100 mT; b) compensation by the hardware and software correction scheme, to overcome the usual frequency increased with the waveform, the magnetic field strength is drastically decreasing issue. Generated from 1 Hz to 500 Hz, magnetic field strength balanced; c) for the triangle wave to produce a constant magnetic field induced electric field characteristics, but also developed a triangular waveform of the magnetic field generator. (2) construct a suitable electrophysiological signals specific wavelet noise reduction algorithms. In using wavelet noise reduction in electrophysiological signals for two characteristics: meet all or none laws; has a certain refractory period. Using square wave haar function as the generating function, constructed a unique wavelet denoising method. Through testing, this method than the traditional means improved filtering effect. (3) proposed a noise reduction algorithm verify the merits of single ion channel approach. All or nothing for ion channel characteristics through the original signal, construct a standard waveform to measure the noise reduction effect. (4) hippocampal cells in the ELF magnetic stimulation of the discharge signal has more rhythm. By autoregressive (Autoregressive, AR) model spectrum analysis showed that magnetic stimulation of hippocampal cells discharge signals smoother lines, indicating that the high frequency component decreased, indicating that the signal has a better rhythm. (5) hippocampal cells under the action of a magnetic field to stimulate electrical activity more active. Spectral analysis using AR model studies have shown that extremely low frequency magnetic fields stimulate hippocampal cells, its AR spectral shift occurred, increased frequency of electrical activity, and show electrical activity more frequently. Random processes and statistical analysis method showed that extremely low frequency magnetic fields stimulate hippocampal cell action potentials when their number increased, peak interval (Inter Spike Interval, ISI) decreases, the potassium ion channel opening hours increased, resting time tends to decrease. This is reported in the literature is the same conclusion. In this paper, two experimental studies have come to a specific field can contribute to the characteristics of electrical activity. From a physiological analysis, Na ~ ion channels in neurons assume a major role, but the potassium ion channel opening will be more active, so it seems that we can draw the following inferences: specific magnetic stimulation on the Na ~-K ~ pump from active to a certain role, although Na ~-K ~ K ~ ion pump flow direction opposite to the ion channel. This is reported in the literature field directly on the Na ~-K ~ pump and increase biofilm activity is consistent, and thus confirms the experimental point of magnetic field on the treatment of neurological disorders.