目的:睡眠通过慢波睡眠(SWS)期间特定振荡事件的精确时间协调来支持系统记忆巩固,即,新皮层缓慢振荡(SOs),丘脑纺锤,和海马波纹。在婴儿中也观察到睡眠对记忆的有益影响,虽然有贡献的地区,尤其是海马和额叶皮层,是不成熟的。这里,我们在大鼠中检查了这些振荡事件的发展及其在早期生命中的耦合。
方法:记录雄性大鼠在出生后第26天和第32天睡眠期间的EEG和海马局部场电位(LFP),大致对应于早期(1-2年)和晚期(9-10年)人类童年,在一组成年大鼠中(14-18周,相当于人类的~22-29岁)。
结果:SO和主轴振幅通常从PD26增加到PD32。并行,额皮质脑电图纺锤波的密度和频率增加,而海马波纹的变化仍然不显着。与纺锤体共存的SO的比例也从PD26增加到PD32。尽管顶叶皮质纺锤体在PD26时已被锁相到去极化的SO-上升状态,但直到PD32才出现额叶皮质SO-纺锤体锁相。童年时海马波纹与纺锤体的共现高于成年大鼠,但是仅在成年大鼠中观察到波纹到可兴奋的纺锤体槽的显着相位锁定。
结论:结果表明,特别是在额皮质网络中,同步丘脑皮质处理的发展已持续进行(即,正面SO-主轴联轴器)。然而,丘脑皮层网络内的同步通常先于丘脑皮层与海马处理的同步,这通过纺锤体-波纹相位耦合的延迟发生来反映。
OBJECTIVE: Sleep supports systems memory consolidation through the precise temporal coordination of specific oscillatory events during slow-wave sleep, i.e. the neocortical slow oscillations (SOs), thalamic
spindles, and hippocampal ripples. Beneficial effects of sleep on memory are also observed in infants, although the contributing regions, especially hippocampus and frontal cortex, are immature. Here, we examined in rats the development of these oscillatory events and their coupling during early life.
METHODS: EEG and hippocampal local field potentials were recorded during sleep in male rats at postnatal days (PD)26 and 32, roughly corresponding to early (1-2 years) and late (9-10 years) human childhood, and in a group of adult rats (14-18 weeks, corresponding to ~22-29 years in humans).
RESULTS: SO and spindle amplitudes generally increased from PD26 to PD32. In parallel, frontocortical EEG
spindles increased in density and frequency, while changes in hippocampal ripples remained nonsignificant. The proportion of SOs co-occurring with
spindles also increased from PD26 to PD32. Whereas parietal cortical
spindles were phase-locked to the depolarizing SO-upstate already at PD26, over frontal cortex SO-spindle phase-locking emerged not until PD32. Co-occurrence of hippocampal ripples with
spindles was higher during childhood than in adult rats, but significant phase-locking of ripples to the excitable spindle troughs was observed only in adult rats.
CONCLUSIONS: Results indicate a protracted development of synchronized thalamocortical processing specifically in frontocortical networks (i.e. frontal SO-spindle coupling). However, synchronization within thalamocortical networks generally precedes synchronization of thalamocortical with hippocampal processing as reflected by the delayed occurrence of spindle-ripple phase-coupling.