摘要
目的:探讨动作电位在无髓鞘神经纤维(C纤维)传导过程中的神经时间编码变化情况,为C纤维对神经信息的加工提供生物学证据和线索. 方法:分离单根家兔隐神经C纤维,给C纤维施加重复的阈上串脉冲刺激,每串有5个脉冲,每串间隔为1 s,串内脉冲间隔为20 ms,重复串刺激200次.刺激过程中记录纤维原始放电,并提取放电序列动作电位峰峰间隔(ISI)序列,观察动作电位沿C纤维传导过程中时间编码方式有无变化及其变化规律. 结果:在动作电位沿纤维传导过程中,所观察的C纤维没有发生传导丢峰,但在传导过程中的时间编码方式发生了变化.根据ISl与刺激间隔大小的关系,ISI分为3个时相,第1时相大于刺激间隔,ISI由20 ms增加到24 ms;第2时相ISI为20 ms,相等于刺激间隔;第3时相ISI减小至最小8 ms,随后稳定在10 ms,小于刺激间隔. 结论:神经信息沿着无髓鞘纤维传播过程中,动作电位ISI排列方式发生了变化,提示动作电位沿着C纤维传播过程中,存在对传递信息的编码加工.
Abstract
AIM: To investigate the conduction coding during the course of action potential (AP) propagating along nonmvelinated nerve fibers. METHODS: Single C fiber of saphenous nerve was separated and then stimulated repetitively by 200 trains of quintuplets superthreshold electrical pulses at a certain interstimulus intervals(inter-stimulus interval 1 s, stimulus interval 20 ms, 5 pulses/train). The AP was recorded and the interspike interval(ISI) was calculated, and the patterns of ISIs during the course of AP propagating were observed. RESULTS: During the course of AP propagating along C fibers, no conduction failure was observed, but patter of ISIs changed. According to the difference between interstimulus and intersipike intervals, ISI had three phases. Phase-1: ISI was longer than interstimulus interval. ISI increased from 20 to 24 ms; Phase-2: ISI equaled to intestimulus interval; and Phase-3: ISI decreased to 8 ms and then reached a stable value of about 10 ms. CONCLUSION: Patterns of ISIs change when APs propagate along the nonmyelinated fibers, suggesting that C fibers have the ability to code the signals propagating along axon by the variance of ISI.
NETL
NSTL
维普
万方数据