[Thalamo-Cortical Mechanisms of Initiation, Maintenance and Termination of Spike-wave Discharges at WAG/Rij rats].

Generalized spike and wave discharges (SWDs) are generated within the cortico-thalamo-cortical system, being an electroencephalographic sign of absence epilepsy. The current work aims to identify mechanisms of SWD initiation, maintenance and termination. Dynamics and directionality of mutual interactions between neocortex (occipital (OC) and frontal (FC) cortex) and thalamus (reticular (RTN) and ventral postero medial (VPM) thalamic nuclei) were investigated. SWD initiation process is revealed several seconds before seizure onset in interaction between all brain areas, except intrathalamic pair (RTN-VPM). This process begins at different moments relatively to SWD onset. The interaction increase is observed earlier and most obviously when thalamus and OC drive FC. The maintenance process (the first few seconds of SWD) is accompanied with high level interaction inside thalamus and increase of driving from thalamus to occipital cortex. Thus interaction from thalamus and occipital cortex to frontal cortex and influence to VPM occur to be below baseline level. At the SWD offset thalamo-cortical interactions were found to return to baseline level quickly.