Sitnikova Evgenia, Hramov Alexander E, Grubov Vadim, Koronovsky Alexey A
Institute of the Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova Street 5A, Moscow 117485, Russia.
Research and Educational Center "Nonlinear Dynamics of Complex Systems", Saratov State Technical University, Saratov, Polytechnicheskaya Street 77, Saratov 410054, Russia ; Faculty of Nonlinear Processes, Saratov State University, Saratov, Astrakhanskaya Street 83, Saratov 410012, Russia.
Neurosci J. 2014;2014:370764. doi: 10.1155/2014/370764. Epub 2014 Jun 23.
The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG) were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time) frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage) and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage), their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.
神经疾病的风险随年龄增长而增加。在失神癫痫的WAG/Rij大鼠模型中，已知癫痫棘波放电的发生率会随着年龄增长而升高。考虑到癫痫棘波放电与生理性睡眠纺锤波之间的密切关系，人们认为癫痫活动随年龄增长而增加可能会影响睡眠纺锤波的时频特征。为了验证这一假设，对5、7和9月龄的WAG/Rij大鼠连续记录脑电图（EEG）。在额叶EEG通道中检测棘波放电和睡眠纺锤波。使用基于小波的算法自动识别睡眠纺锤波。利用EEG信号的连续小波变换确定睡眠纺锤波的瞬时（时间定位）频率，并进一步研究纺锤波内频率动态。研究发现，在5月龄大鼠中，癫痫活动尚未完全发展（临床前期），睡眠纺锤波的瞬时频率从开始到结束都有所增加。在7和9月龄时，当动物出现成熟且更长时间的癫痫放电（症状期）时，它们的睡眠纺锤波没有显示出固有频率的变化。目前的数据表明，WAG/Rij大鼠中癫痫活动随年龄增长而增加会影响睡眠纺锤波频率的固有动态。
