title: Susceptibility of brainstem to kindling and transfer to the forebrain.
abstract: OBJECTIVE
  The kindling of seizures with stimulation of brainstem sites has been reported inconsistently in the literature. The characteristics of the kindling observed, involving high intensities of stimulation and immediate onset of generalized tonic-clonic convulsions, raise questions regarding the nature of kindling from these sites.
  
  
  METHODS
  We implanted chronic electrodes in either the nucleus reticularis pontis oralis (RPO), mesencephalic reticular formation (MRF), dorsal periaqueductal gray (dPAG), or ventrolateral periaqueductal gray (vlPAG) in male Long-Evans rats, with a recording electrode in the amygdala. Rats received conventional high-frequency kindling stimulation once daily for 30 days. To test for transfer, we kindled the amygdala beginning 7 weeks after the last brainstem kindling trial.
  
  
  RESULTS
  Tonic-clonic seizures were evoked by stimulation from all brainstem sites. Seizures were brief and were associated with characteristic low-amplitude high-frequency afterdischarge (AD). Kindling of the dPAG resulted in the development of classic AD and increased AD duration. Prior kindling of the dPAG facilitated subsequent kindling of the amygdala; however, no transfer was observed with prekindling of other brainstem sites.
  
  
  CONCLUSIONS
  The variability in the response to kindling stimulation suggests that certain brainstem sites are resistant to kindling, whereas other sites are more susceptible to kindling but are still relatively resistant in comparison to sites in the forebrain. The development of classic AD in later trials of dPAG stimulation suggests that epileptogenesis can occur even in the initial absence of classic AD when low-amplitude high-frequency AD is present.
authors.affiliation: Department of Anatomy and Cell Biology Neural Systems and Plasticity Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Ann
authors.initials: A
authors.lastname: Lam
authors.forename: Naomi
authors.initials: N
authors.lastname: Whelan
authors.forename: Michael E
authors.initials: ME
authors.lastname: Corcoran
mesh_terms: D000679:Amygdala / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D004830:Epilepsy, Tonic-Clonic / Q000503:physiopathology*; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D009431:Neural Conduction / Q000502:physiology; D016548:Prosencephalon / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012640:Seizures