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外周感觉神经元通过动作电位序列对信号进行编码,这些动作电位序列经过突触传递最终到达脑部。但是各种脉冲序列如何通过神经元之间的化学突触进行传递依然是一个悬而未决的问题。研究了初级传入Aδ纤维与背角神经元之间各种动作电位序列的突触传递过程。用于刺激的规则、周期、随机脉冲序列由短簇脉冲或单个脉冲构成。定义“事件”(event)为峰峰间期(interspike interval)小于或等于规定阈值的最长动作电位串,然后从脉冲序列中提取事件间间期(in-terevent interval, IEI)。用时间-IEI图与回归映射的方法分析IEI序列,结果表明在突触后输出脉冲序列中可以检测到突触前脉冲序列的主要时间结构特征,特别是在短簇脉冲作为刺激单位时。通过计算输入与输出脉冲序列的互信息,发现短簇脉冲可以更可靠地跨突触传递由输入序列携带的神经信息。这些结果表明外周输入脉冲序列的主要时间结构特征可以跨突触传递,在突触传递神经信息的过程中短簇脉冲更为有效。这一研究在从突触传递角度探索神经信息编码方面迈出了一步。
Peripheral sensory neurons encode signals through a series of action potentials that eventually reach the brain via synaptic transmission. But how the various pulse trains pass through chemical synapses between neurons remains an open question. The synaptic transmission of various action potential sequences between primary afferent Aδ fibers and dorsal horn neurons was studied. Rules for stimuli, periods, random pulse sequences consist of short cluster pulses or single pulses. Define the longest action potential string whose “event” is the interspike interval less than or equal to the specified threshold and then extract the in-terevent interval (IEI) from the pulse sequence. The IEI sequence was analyzed by time-IEI and regression mapping. The results showed that the main temporal structure of the pre-synaptic pulse sequence was detected in the post-synaptic output pulse sequence, especially when the short cluster pulse was used as the stimulation unit. By computing the mutual information of the input and output pulse sequences, it is found that the short cluster pulses can more reliably transmit the neural information carried by the input sequence across the synapse. These results indicate that the main temporal structural features of the peripheral input pulse sequence can be transmitted across the synapse, and short clustering pulses are more effective in synaptic transmission of neural information. This research takes a step toward exploring neural coding from the perspective of synaptic transmission.