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目的研究前馈抑制和反馈抑制在控制大脑海马组织CA1锥体神经元动作电位发放中各自的作用强度随时间变化的特性。方法在大鼠海马CA1区的输入通路Schaffer侧支和输出通路alveus上分别植入正向和反向刺激电极。在锥体神经元胞体层记录正向和反向双刺激诱发的群峰电位,并利用双正向、先反后正以及先正后反的不同双刺激组合的响应,分析计算两种抑制的作用,在体分别考察它们的短时程作用过程。结果两种抑制的协同作用在第一个刺激后的50 ms内比较强,第二个刺激诱发的群峰电位的抑制超过50%,在10 ms以内则几乎完全被抑制。并且,在10~50 ms,随时间的缩短,反馈抑制作用的比例增大;但在3~7 ms时间段存在明显的反馈抑制减弱时期。结论反馈抑制作用期与动作电位不应期之间并不能衔接,是快速有力的前馈抑制作用补充了反馈抑制与不应期之间的抑制减弱期。
OBJECTIVE: To study the effect of feedforward suppression and feedback inhibition on the action potentials of CA1 pyramidal neurons in the hippocampus CA1 distribution over time. Methods Schaffer collateral and output alveus in the hippocampal CA1 region of rats were implanted with positive and negative stimulation electrodes respectively. The peak potentials induced by both forward and reverse double stimulation were recorded in the soma of pyramidal neurons, and the responses of the two types of inhibition were analyzed and calculated using the response of different bi-stimulus combinations of bi-normal, anterior-posterior and anterior-posterior. Role in the body separately examine their short-term role in the process. Results The synergistic effect of the two inhibitions was stronger within 50 ms after the first stimulation. The suppression of the peak potentials induced by the second stimulation was over 50% and almost completely suppressed within 10 ms. Moreover, the proportion of feedback inhibition increased with time shortened from 10 to 50 ms, but there was a significant period of feedback suppression during the period of 3 to 7 ms. Conclusions The feedback inhibitory period and the action potential refractory period can not converge. It is a fast and powerful feedforward inhibition that complements the suppression weakening period between feedback inhibition and refractory period.