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背景:近年来研究结果表明经颅磁刺激对学习记忆能力产生影响,一些研究也开始探讨在模拟脑电节律条件下的磁场对记忆能力的影响。目的:探讨磁场对记忆再现能力的影响及其作用机制。设计:随机对照实验。单位:天津医科大学医学影像学系和天津大学精密仪器及光电子工程学院。材料:实验于2002-02/2004-02在天津大学生物医学工程实验室及天津医科大学电镜中心完成,25只Wistar大鼠和5只家猫由天津医科大学实验动物中心提供。干预:将25只Wister大鼠,随机分为5组,4个实验组和1个对照组,每组5只大鼠。实验1～4组接受调制脉冲磁场刺激,但各组作用时间及调制频率变化规律不同。实验1组接受α节律(10Hz)调制脉冲磁场刺激;实验2组接受β节律(20Hz)调制脉冲磁场刺激;实验3组采用先α节律后β节律波刺激;实验4组采用先β节律后α节律波刺激。记录大鼠记忆再现能力和脑内神经递质的变化。5只家猫先采用先α节律后β节律的脉冲磁场作用20min,比较磁场作用前后家猫的脑电节律的变化。主要观察指标:①采用改良“十”字迷宫法测试大鼠长时空间记忆再现能力的变化。②用高效液相色谱仪检测磁场作用后大鼠脑海马神经递质。③利用多导生理记录仪记录家猫脑电功率的变化。结果:25只Wistar大鼠和5只家猫均进入结果分析。①大鼠记忆再现能力比较:弱磁场刺激后5h实验2组、4组明显高于对照组犤(11.81±2.80,16.39±3.09,5.77±2.41)s,(P<0.05,P<0.01)犦。②大鼠脑海马多巴胺含量:实验组明显高于对照组犤(192.72±18.66,148.17±24.52)ng/g,(P<0.05)犦。③家猫β节律变化功率变化:脑电β频率段在功率谱中的面积百分比与刺激前相比显著增加(23.0±3.4,14.2±1.3)%。结论:大多数模拟脑电节律的弱磁场作用明显降低大鼠长时记忆再现能力,但特殊节律的弱磁场可能会提高大鼠记忆再现能力。这些影响与受钙离子内流及突触小泡调控的海马神经递质释放有关。
BACKGROUND: In recent years, the results show that transcranial magnetic stimulation has an impact on learning and memory ability, and some researches have begun to explore the effect of magnetic field on memory ability under the condition of simulated electroencephalogram. Objective: To explore the effect of magnetic field on memory ability and its mechanism. Design: Randomized controlled experiment. Unit: Tianjin Medical University Department of Medical Imaging and Tianjin University Institute of Precision Instruments and Optoelectronics Engineering. MATERIALS: Experiments were performed at Biomedical Engineering Laboratory of Tianjin University and Electron Microscopy Center of Tianjin Medical University from February 2002 to February 2004. Twenty-five Wistar rats and five domestic cats were provided by Experimental Animal Center of Tianjin Medical University. Intervention: 25 Wister rats were randomly divided into 5 groups, 4 experimental groups and 1 control group, 5 rats in each group. Experiment 1 ~ 4 groups received modulated magnetic field stimulation, but the effect of different time and modulation frequency of each group varied. The experimental group 1 was stimulated by α rhythm (10 Hz) modulated pulsed magnetic field; the experimental group 2 was stimulated by β rhythm (20 Hz) modulated pulsed magnetic field; the third group was stimulated by β rhythm before α rhythm; Rhythm wave stimulation. Changes of memory ability and neurotransmitter in brain were recorded. Five domestic cats used the pulse rhythm of β-rhythm before α rhythm for 20 minutes, and compared the changes of EEG before and after domestic magnetic field. MAIN OUTCOME MEASURES: ① The changes of long-term memory ability of rats were tested by modified “X” maze test. ② Hippocampal neurotransmitter was detected by high performance liquid chromatography after magnetic field. ③ use of multi-channel physiological recorder recording cats brain electrical power changes. Results: Twenty-five Wistar rats and five domestic cats were involved in the result analysis. ① Comparison of memory reproducibility in rats: The rats in group 2 and group 4 at 5h after weak magnetic field stimulation were significantly higher than those in control group (11.81 ± 2.80, 16.39 ± 3.09 and 5.77 ± 2.41) s (P <0.05, P <0.01) . ② The content of dopamine in the hippocampus: The experimental group was significantly higher than the control group (192.72 ± 18.66, 148.17 ± 24.52) ng / g, (P <0.05) 犦. (3) The power variation of β rhythm changes in domestic cats: The area percentage of the β frequency band in the power spectrum increased significantly (23.0 ± 3.4,14.2 ± 1.3)% compared with that before stimulation. CONCLUSION: Most of the effects of weak magnetic fields that mimic EEG play a significant role in long-term memory reproduction in rats, but weak magnetic fields with special rhythms may improve the ability of memory reproduction in rats. These effects are related to the release of neurotransmitters in the hippocampus regulated by calcium influx and synaptic vesicles.