title: Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats.
abstract: 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.
authors: Institute of the Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova Street 5A, Moscow 117485, Russia.
authors: Evgenia
authors: E
authors: Sitnikova
authors: 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.
authors: Alexander E
authors: AE
authors: Hramov
authors: 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.
authors: Vadim
authors: V
authors: Grubov
authors: Research and Educational Center "Nonlinear Dynamics of Complex Systems", Saratov State Technical University, Saratov, Polytechnicheskaya Street 77, Saratov 410054, Russia ; Saratov State University, Astrakhanskaya Street 83, Saratov 410012, Russia.
authors: Alexey A
authors: AA
authors: Koronovsky