Eschenko Oxana, Ramadan Wiâm, Mölle Matthias, Born Jan, Sara Susan J
Neuromodulation, Neuroplasticity and Cognition, Centre National de la Recherche Scientifique (CNRS), UMR 7102, 75005 Paris, France.
Learn Mem. 2008 Apr 2;15(4):222-8. doi: 10.1101/lm.726008. Print 2008 Apr.
High-frequency oscillations, known as sharp-wave/ripple (SPW-R) complexes occurring in hippocampus during slow-wave sleep (SWS), have been proposed to promote synaptic plasticity necessary for memory consolidation. We recorded sleep for 3 h after rats were trained on an odor-reward association task. Learning resulted in an increased number SPW-Rs during the first hour of post-learning SWS. The magnitude of ripple events and their duration were also elevated for up to 2 h after the newly formed memory. Rats that did not learn the discrimination during the training session did not show any change in SPW-Rs. Successful retrieval from remote memory was likewise accompanied by an increase in SPW-R density and magnitude, relative to the previously recorded baseline, but the effects were much shorter lasting and did not include increases in ripple duration and amplitude. A short-lasting increase of ripple activity was also observed when rats were rewarded for performing a motor component of the task only. There were no increases in ripple activity after habituation to the experimental environment. These experiments show that the characteristics of hippocampal high-frequency oscillations during SWS are affected by prior behavioral experience. Associative learning induces robust and sustained (up to 2 h) changes in several SPW-R characteristics, while after retrieval from remote memory or performance of a well-trained procedural aspect of the task, only transient changes in ripple density were induced.
高频振荡，即慢波睡眠（SWS）期间海马体中出现的尖波/涟漪（SPW-R）复合体，被认为有助于促进记忆巩固所需的突触可塑性。在大鼠接受气味-奖励关联任务训练后，我们记录了3小时的睡眠情况。学习导致学习后SWS的第一个小时内SPW-R的数量增加。新形成记忆后的2小时内，涟漪事件的幅度及其持续时间也有所增加。在训练过程中未学会辨别任务的大鼠，其SPW-R没有任何变化。相对于之前记录的基线，从远期记忆中成功提取记忆同样伴随着SPW-R密度和幅度的增加，但这种影响持续时间短得多，且不包括涟漪持续时间和幅度的增加。当仅对大鼠执行任务的运动部分给予奖励时，也观察到涟漪活动的短暂增加。在适应实验环境后，涟漪活动没有增加。这些实验表明，SWS期间海马体高频振荡的特征受先前行为经验的影响。联想学习会在几个SPW-R特征上诱导强大且持续（长达2小时）的变化，而从远期记忆中提取记忆或执行训练有素的任务程序方面后，仅会诱导涟漪密度的短暂变化。
