Time-frequency characteristics and dynamics of sleep spindles in WAG/Rij rats with absence epilepsy.
In rat models of absence epilepsy, epileptic spike-wave discharges appeared in EEG spontaneously, and the incidence of epileptic activity increases with age. Spike-wave discharges and sleep spindles are known to share common thalamo-cortical mechanism, suggesting that absence seizures might affect some intrinsic properties of sleep spindles. This paper examines time-frequency EEG characteristics of anterior sleep spindles in non-epileptic Wistar and epileptic WAG/Rij rats at the age of 7 and 9 months. Considering non-stationary features of sleep spindles, EEG analysis was performed using Morlet-based continuous wavelet transform. It was found, first, that the average frequency of sleep spindles in non-epileptic Wistar rats was higher than in WAG/Rij (13.2 vs 11.2 Hz). Second, the instantaneous frequency ascended during a spindle event in Wistar rats, but it was constant in WAG/Rij. Third, in WAG/Rij rats, the number and duration of epileptic discharges increased in a period between 7 and 9 months of age, but duration and mean value of intra-spindle frequency did not change. In general, age-dependent aggravation of absence seizures in WAG/Rij rats did not affect EEG properties of sleep spindles; it was suggested that pro-epileptic changes in thalamo-cortical network in WAG/Rij rats might prevent dynamic changes of sleep spindles that were detected in Wistar.
Institute of the Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova str., 5A, Moscow 117485, Russia. Electronic address: jenia-s@mail.ru.
Evgenia
E
Sitnikova
Faculty of Nonlinear Processes, Saratov State University, Saratov, Astrakhanskaya str., 83, Saratov 410012, Russia; Research-Educational Center 'Nonlinear Dynamics of Complex Systems', Saratov State Technical University, Saratov, Polytechnicheskaya str., 77, Saratov 410054, Russia. Electronic address: hramovae@gmail.com.
Alexander E
AE
Hramov
Faculty of Nonlinear Processes, Saratov State University, Saratov, Astrakhanskaya str., 83, Saratov 410012, Russia; Research-Educational Center 'Nonlinear Dynamics of Complex Systems', Saratov State Technical University, Saratov, Polytechnicheskaya str., 77, Saratov 410054, Russia. Electronic address: vvgrubov@gmail.com.
Vadim
V
Grubov
Faculty of Nonlinear Processes, Saratov State University, Saratov, Astrakhanskaya str., 83, Saratov 410012, Russia; Research-Educational Center 'Nonlinear Dynamics of Complex Systems', Saratov State Technical University, Saratov, Polytechnicheskaya str., 77, Saratov 410054, Russia. Electronic address: alexey.koronovskii@gmail.com.
Alexey A
AA
Koronovsky
D000367:Age Factors; D000818:Animals; D058256:Brain Waves / Q000235:genetics / Q000502:physiology*; D004195:Disease Models, Animal; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000235:genetics / Q000503:physiopathology*; D005583:Fourier Analysis; D008817:Mice, Mutant Strains; D017711:Nonlinear Dynamics; D051381:Rats; D017208:Rats, Wistar; D012894:Sleep Stages / Q000235:genetics / Q000502:physiology*; D013997:Time Factors
Absence epilepsy; CWT; Continuous wavelet transform; GLM; Instantaneous frequency dynamics; RTN; SWD; Sleep spindles; TC; WAG/Rij rats; continuous wavelet transform; general linear model; reticular thalamic nucleus; spike-wave discharges; thalamocortical