Postnatal differentiation of firing properties and morphological characteristics in layer V pyramidal neurons of the sensorimotor cortex
Postnatal differentiation of firing properties and morphological characteristics in layer V pyramidal neurons of the sensorimotor cortex
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DOI：
10.1016/s0306-4522(97)00463-6
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发表时间：
1998-04-01
期刊：
影响因子：
3.3
通讯作者：
Avanzini, G
中科院分区：
文献类型：
--
作者：
Franceschetti, S;Sancini, G;Avanzini, G
用生后3天至22天的细胞内记录方法，分析了注射生物细胞素行形态重建的大鼠感觉运动皮质217个V层锥体神经元的放电特性的成熟轮廓。从出生后第2周开始，锥体神经元可根据是否存在峰频率适应而分为适应性规则棘波和非适应性规律性棘波。非适应性规则棘波神经元的比例在出生后第二周非常高(53%)，并随着年龄的增长而逐渐下降，同时出现了新的固有爆裂性神经元(第三周开始)，其比例从P14-P16大鼠的23%逐渐增加到成年大鼠的46%。非适应性规则放电神经元与固有爆发性神经元具有共同的生理特征，即动作电位更快，异常整流效应更显著，去极化后电位一致，这是它们区别于适应性规则放电神经元的主要特征。此外，爆裂型和非适应性规则棘波神经元的特征是基底树突起呈圆形分布，顶端树突树枝扩张，这与适应性规则棘波神经元不同，表现为更简单的树突树枝。这些形态特征可见于出生后第二周开始的未成熟的内在爆裂性神经元，以及从出生后第二周开始的未成熟的非适应性规则尖峰神经元。这些发现表明，相当一部分未成熟的非适应性规则尖峰神经元致力于成为爆发者，并且一旦维持爆发式放电的离子电流足够强，它们在出生后第二周就被转化为本质爆裂性神经元。未成熟的非适应性规则放电神经元和固有爆发性神经元的较快动作电位提示这些神经元类神经元中有较高密度的Na+通道：Na+电流的成熟增加，即其持续比例的增加，可能代表了非适应性规则放电神经元向本质爆发性神经元转变的关键事件。(C)1998年IBRO。爱思唯尔科学有限公司出版。
The maturational profile of the firing characteristics of 217 layer V pyramidal neurons of rat sensorimotor cortex, injected with biocytin for morphological reconstruction, was analysed by means of intracellular recordings made between postnatal day (P)3 and 22. Starting from the onset of the second postnatal week, the pyramidal neurons could be differentiated as adapting or non-adapting regular spiking on the basis of the presence or absence of spike frequency adaptation. The percentage of non-adapting regular spiking neurons was very high during the second postnatal week (53%) and progressively decreased with age, concurrently with the appearance of the new class of intrinsically bursting neurons (beginning of the third week) whose percentage progressively increased from 23%, found in P14-P16 rats, to 46% in adult rats. Non-adapting regular spiking neurons were found to share with intrinsically bursting neurons several physiological characteristics comprehending faster action potentials, more prominent effect of anomalous rectification and consistent depolarizing afterpotentials, that differentiated them from the adapting regular spiking neurons. Moreover, intrinsically bursting and non-adapting regular spiking neurons were characterized by a round-shaped distribution of basal dendrites and expanded apical dendritic arborization, that differentiated them from the adapting regular spiking neurons showing a simpler dendritic arborization. These morphological hallmarks were seen In immature intrinsically bursting neurons as soon as they became distinguishable, and in immature non-adapting regular spiking neurons starting from the onset of the second postnatal week.These findings suggest that a significant subpopulation of immature non-adapting regular spiking neurons are committed to becoming bursters, and that they are converted into intrinsically bursting neurons during the second postnatal week, as soon as the ionic current sustaining the burst firing is sufficiently strong. The faster action potentials in both immature non-adapting regular spiking and intrinsically bursting neurons suggest a higher density of Na+ channels in these neuronal classes: the maturational increase in Na+-current, namely of its persistent fraction, may represent the critical event for the conversion of the non-adapting regular spiking neurons into the intrinsically bursting ones. (C) 1998 IBRO. Published by Elsevier Science Ltd.