摘要目的:探讨生后早期小鼠上丘视觉感知层神经元的动作电位发放模式及不同放电模式神经元类型的电生理学特性。方法:实验研究。采用离体脑片全细胞膜片钳技术，对57只14~20日龄的健康雄性C57BL/6J小鼠（体重5.0~8.9 g）上丘视觉感知层神经元进行记录。在电流钳模式下，基于去极化电流产生的第一个动作电位分析动作电位特征，并采用去极化的步进电流来记录神经元动作电位的发放模式。通过层次聚类法分析神经元动作电位的发放模式，并对不同放电模式神经元的主动电学特性进行分析和比较。结果:共获得135个上丘视觉感知层神经元的完整全细胞膜片钳记录，对神经元动作电位发放模式进行聚类分析，结果发现3种放电模式神经元：强直发放（97个，72%）、阶段性发放（26个，19%）和单个发放（12个，9%），其动作电位发放数目分别为（13.30±7.38）、（3.73±3.61）、（0.83±0.39）个，差异有统计学意义（ P<0.001）。3种放电模式神经元对注入步进电流的膜电位反应差异无统计学意义（ P>0.05）。3种放电模式神经元动作电位的幅值分别为（60.45±12.22）（53.67±13.20）（44.04±12.92）mV，后超极化幅值分别为（13.45±13.79）（12.02±13.11）（20.75±2.85）mV，最大上升速率分别为（171.29±77.46）（130.14±61.83）（78.89±37.08）V/s，最大下降速率分别为（-76.33±33.61）（-68.17±31.65）（-47.97±13.92）V/s，差异均有统计学意义（均 P<0.05）；3种放电模式神经元的静息膜电位，动作电位的阈值、半峰宽、后超极化时间差异无统计学意义（均 P>0.05）。 结论:生后早期小鼠上丘视觉感知层神经元存在强直发放、阶段性发放和单个发放3种放电模式神经元，这3种放电模式神经元的动作电位幅值、后超极化幅值、最大上升速率、最大下降速率存在明显差异。

abstractsObjective:To investigate the action potential firing patterns of neurons in the visual sensory layers of the superior colliculus in early postnatal mice and the electrophysiological characteristics of neurons with different firing patterns.Methods:This experimental study utilized whole-cell patch-clamp recordings performed on neurons in the visual sensory layers of the superior colliculus using brain slices from 57 healthy male C57BL/6J mice aged 14 to 20 days (weighing 5.0 to 8.9 g) using brain slices. In current-clamp mode, action potential characteristics were analyzed based on the first action potential generated by depolarizing current, and the firing patterns of neurons were recorded using step depolarizing currents. Neuronal firing patterns were analyzed using hierarchical clustering, and the active electrical properties of neurons with different firing patterns were compared.Results:A total of 135 neurons from the visual sensory layers of the superior colliculus were successfully recorded. Cluster analysis of the neuronal firing patterns identified three types of firing patterns: tonic firing (97, 72%), phasic firing (26, 19%), and single firing (12, 9%). The number of action potentials for each firing pattern was 13.30±7.38, 3.73±3.61, and 0.83±0.39, respectively, with significant differences ( P<0.001). There was no significant difference in the membrane potential response to step currents among the three firing pattern types ( P>0.05). The action potential amplitudes were (60.45±12.22), (53.67±13.20), and (44.04± 12.92) mV, and the afterhyperpolarization amplitudes were (13.45±13.79), (12.02±13.11), and (20.75±2.85) mV, respectively. The maximum rising slopes were (171.29±77.46), (130.14±61.83), and (78.89±37.08) V/s, and the maximum falling slopes were (-76.33±33.61), (-68.17±31.65), and (-47.97±13.92) V/s, respectively, with all differences being statistically significant (all P<0.05). There were no significant differences in the resting membrane potential, action potential threshold, half-width, and afterhyperpolarization duration among the three firing pattern types (all P>0.05). Conclusions:In the early postnatal mice, neurons in the visual sensory layers of the superior colliculus exhibit three distinct firing patterns: tonic, phasic, and single firing. These firing pattern types show significant differences in action potential amplitude, afterhyperpolarization amplitude, maximum rising slopes, and maximum falling slopes.