深部脑刺激在帕金森和癫痫等脑部疾病治疗中的应用不断发展,它使用的电刺激波形通常为窄脉冲。但是,对于单相脉冲与双相脉冲的刺激作用之间的差别还缺乏全面的认识。为了研究不同波形脉冲对于深部脑组织的刺激作用,在麻醉大鼠海马CA1区的输入和输出轴突纤维上,分别施加不同极性的或者不同方式的(单个或连续)单相和双相脉冲,考察CA1区神经元单细胞和神经元群体在刺激作用下的响应,以定量分析不同刺激波形的作用效果。共计18次动物实验结果如下:1)CA1区输入通道的小强度单个刺激顺向诱发单元锋电位时,以兴奋性相位为前相的双相脉冲和兴奋性单相脉冲的诱发率(分别为69.2%±10.4%和65.0%±10%)显著高于以非兴奋性相位为前相的双相脉冲和非兴奋性单相脉冲的诱发率(分别为28.8%±9.5%和34.2%±12.5%)(n=6);而且,双相脉冲的作用效果取决于前相,与无后相的单相脉冲的作用效果没有显著差别。2)CA1区输出通道的大强度单个刺激逆向诱发群峰电位时,双相脉冲的作用仍然与单相脉冲接近(n=6),由其前相主导,后相的作用较小。3)在CA1区输出通道逆向的100 Hz持续高频串刺激期间,起始0.5 s时间内单相脉冲引起群峰电位的幅值下降(54.2%±21.3%)显著高于前相与其一致的双相脉冲所引起的幅值下降(39.0%±10.2%)(n=6),说明高频串刺激时单相脉冲的作用比双相脉冲要强,但是单相脉冲可能造成神经组织的损伤。因此,长时间的高频刺激治疗应采用双相脉冲。这些研究结果对于深入了解深部脑刺激的作用机制以及安全有效地推广其临床应用都具有重要意义。
Deep brain stimulation( DBS) has been developed for treating brain diseases such as Parkinson 's disease and epilepsy. Narrow pulses are the most commonly used stimulation waveforms of DBS. However,the differences between the stimulation effects of monophasic pulses and biphasic pulses are not clear yet. To investigate the different stimulation effects on deep brain tissue by different pulse waveforms,monophasic and biphasic pulses with different polarity and different patterns( single or train) were respectively applied in the afferent fibers and the efferent fibers of the hippocampus CA1 region in anaesthetized rats. Responses of single neurons and neuronal populations in the CA1 region were examined to quantitatively analyze the effect of different stimulation waveforms. Results of total 18 animal experiments were shown as following: 1) For single pulses stimulation with low intensity on the afferent fibers to evoke unit spikes orthodromically in the CA1 region,the evoked ratios of excitatory-phase-first biphasic and excitatory-phase monophasic were 69. 2% ±10. 4% and 65. 0% ± 10%( n = 6),respectively. These ratios were significantly higher than the evoked ratiosof non-excitatory-phase-first biphasic and non-excitatory-phase monophasic: 28. 8% ± 9. 5% and 34. 2% ±12. 5%( n = 6),respectively. In addition,the stimulation effect of biphasic pulses was dominated by first phases and was not significantly different from the effect of monophasic pulses without second phases. 2) For single pulses on the efferent fibers to evoke population spikes antidromically in the CA1 region,the stimulation effect of biphasic pulses was still similar to the effect of monophasic pulses without second phases( n = 6). The effect of biphasic pulses was dominated by their first phases without significant effects of the second phases. 3)During 100 Hz high-frequency antidromic stimulations on the efferent fibers of CA1 region,in the 0. 5 s period at the beginning of stimulation,the amplitude suppression