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1/f波电刺激前后脑电功率谱和复杂度的分析研究

Analysis of Eeg Power Spectrum and Complexity before and after 1/f-Wave Electrical Stimulation

【作者】 勾慧兰

【导师】 胡世强;

【作者基本信息】 河北科技大学 , 生物医学工程, 2010, 硕士

【摘要】 电刺激在神经系统疾病治疗中的应用已经非常普遍。目前常用的治疗方法主要有脑深部电刺激(Deep brain stimilation,DBS)、迷走神经电刺激(Vagus nerve stimulation, VNS)、跨颅磁刺激(Transcranial magnetic stimulation,TMS)和经皮神经电刺激(Transcutaneous electrical nerve stimulation,TENS)。这几种方法都是通过改变脉冲波形和幅度达到治疗目的的,而这些脉冲的波形和幅度都是固定的,对人体大脑进行长时间多次刺激后,大脑逐渐适应电脉冲的刺激,从而导致治疗效果减弱,针对这一状况,本文设计研制了1/f波电刺激器。1/f波电脉冲是随机变化的信号,与幽静小溪的潺潺流水和徐徐袭来的清风的变化规律,以及人在安静、愉快时的α脑电波、心律周期等生物信号的变化节奏相吻合,在治疗神经系统疾病领域有很好的发展前景。对失眠、焦虑、抑郁、神经衰弱病人大脑皮层的特定部位进行1/f波电刺激,以达到恢复人体神经系统的安眠、镇静、抗焦虑、抗抑郁的生物效应的目的。并采集刺激前、后的脑电信号,分别进行分析研究,进一步探讨治疗的效果。在硬件设计中,微功耗和便携式成为设计的主要考虑因素。1/f波电刺激系统硬件主要由51单片机P89C58BP、ADC0809及集成运算放大器构成,具有结构简单、成本低、体积小、便于携带等特点;脑电数据的采集传输部分主要由USB型单片机C8051F320、微功耗单片机MSP430F149和放大器组成。根据MSP430F149单片机具有超低功耗的特点,利用其高精度12位AD转换器采集2路1/f波电刺激前、后的脑电信号,并同时进行存储及传输。C8051F320内自带USB控制器,因此硬件电路设计简单,可以实现数据的快速传输。程序设计均用单片机C51语言开发。脑电的功率谱特征与脑力疲劳程度之间有着密切的关系,能灵敏地反应出脑力疲劳程度的变化。对刺激前、后的脑电信号进行功率谱分析,表明1/f波电刺激在很大程度上缓解了患者的精神状态。复杂度从大脑接受和处理信息量的角度反映了大脑处于不同负荷状态下的活动情况。对刺激前、后的脑电信号进行复杂性测度分析,求取近似熵。由于近似熵在刺激前、后具有显著差异,表明1/f波电刺激能使混沌的大脑变得活跃,增强大脑的思维跳跃,促进大脑的活动。由此可见,1/f波电刺激在治疗神经系统疾病上,能够缓解失眠、焦虑、抑郁、神经衰弱等,并且具有很好的疗效。

【Abstract】 The application of electrical stimulation in the treatment of diseases of the nervous system has been very common. The current commonly used main treatment methods are deep brain stimulation, vagus nerve stimulation, Transcranial magnetic stimulation and transcutaneous electrical nerve stimulation. These methods are by changing the pulse shape and amplitude for therapeutic purposes, but these pulse waveform and amplitude are fixed, human brain after prolonged repeated stimulation, the brain gradually adapt to electrical pulse stimulation, resulting in decreased therapeutic effect, in response to this situation, this paper designed a 1/f-wave stimulator.1/f-wave electrical pulse is random changes in signal, with the quiet stream gurgling water, and gently hit the breeze of change in the law, as well as the changes in rhythm anastomosis of the biological signals, when a-brain waves and heart rate cycle are in quiet or pleasant, in the treatment of nervous system disease has good prospects for development.The 1/f-wave electrical pulse Stimuluses specific parts of the cerebral cortex of patients who are insomnia, anxiety, depression, neurasthenia, and in order to achieve the purpose of restoring the biological effects of human nervous system of sleep, sedation, anxiety, antidepressants.In hardware design, micropower and portable are the main design considerations. 1/f-wave electrical stimulation system hardware mainly compose by the 51 SCM P89C58BP, ADC0809 and integrated op-amp composition, which has a simple structure, low cost, small size, easy to carry and other characteristics; EEG data collection transfer part is made up of the USB-based MCU C8051F320, micro-power microcontroller MSP430F149 and the amplifier. According to the ultra-low power features of MSP430F149 MCU, using its high-precision 12-bit A/D converter captures 2-way 1/f-wave electric stimulation before and after the EEG, and at the same time storage and transmission. C8051F320 builted-in USB controller, so the hardware circuit design simple and fast data transfer can be achieved. Programming languages are developed with MCU C51.EEG power spectral characteristics and mental fatigue have a close relationship between the degree, can sensitively reflect the changes in mental fatigue. Analyzing the power spectrum of the before and after Stimulating EEG shows that 1/f-wave electrical stimulation largely alleviates the patient’s mental state. The complexity reflects the brain at different load condition of the activities from the angle of the brain to receive and handle the amount of information. Analyzing the complexity measure of pre and post stimulating EEG, then strike the approximate entropy. As the approximate entropy in stimulating pre and post significant differences, indicating that 1/f-wave electrical stimulation of the brain can become active chaotic and enhance the brain’s thinking, jumping to promote brain activity. Thus, 1/f-wave electrical stimulation in the treatment of nervous system diseases, which can alleviate insomnia, anxiety, depression, neurasthenia, and have good results.

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