title: Spike-wave discharges in WAG/Rij rats are preceded by delta and theta precursor activity in cortex and thalamus.
abstract: OBJECTIVE
  In order to unravel the mechanisms underlying the "sudden" onset of spontaneous absences in genetically prone subjects, we investigated the immediate precursors of spike-wave discharges (SWDs) produced in cortico-thalamo-cortical neuronal networks.
  
  
  METHODS
  A time-frequency analysis of the cortical and thalamic ECoG of WAG/Rij rats was accomplished with a continuous wavelet decomposition of SWDs, 3 s prior to the onset of SWDs (pre-SWD), and in control periods devoid of SWDs.
  
  
  RESULTS
  The pre-SWD ECoG consisted of delta and theta components in 80-90% of all SWDs simultaneously in cortex and thalamus, the co-occurrence of delta and theta was rare (7%) during control periods. The occurrence of delta and theta events in pre-SWDs in the cortex preceded that in the thalamus. The frequency of theta component in cortex correlated positively with that in thalamus, this correlation was less strong for delta.
  
  
  CONCLUSIONS
  Precursors of SWDs comprise of delta and theta, their co-occurrence is typical for non-epileptic periods. Thalamic and cortical theta are strongly related. Rhythmic precursors appear earlier in cortex than in thalamus, and this is in line with the cortical origin of SWD.
  
  
  CONCLUSIONS
  Simultaneous presence of delta and theta events in EEG is a condition for the occurrence of SWDs.
authors.affiliation: Donders Center for Cognition, Radboud University Nijmegen, Nijmegen, The Netherlands. g.vanluijtelaar@donders.ru.nl
authors.forename: Gilles
authors.initials: G
authors.lastname: van Luijtelaar
authors.forename: Alexander
authors.initials: A
authors.lastname: Hramov
authors.forename: Evgenia
authors.initials: E
authors.lastname: Sitnikova
authors.forename: Alexei
authors.initials: A
authors.lastname: Koronovskii
mesh_terms: D000465:Algorithms; D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D003700:Delta Rhythm / Q000502:physiology*; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation; D004827:Epilepsy / Q000235:genetics / Q000503:physiopathology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012984:Software; D013238:Stereotaxic Techniques; D013686:Telemetry; D013788:Thalamus / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology*; D058067:Wavelet Analysis