title: Modulation of excitability by continuous low- and high-frequency stimulation in fully hippocampal kindled rats.
abstract: BACKGROUND
  Low- and high-frequency stimulation (LFS and HFS, respectively) have been, reported to modify seizure characteristics in rats. We here report effects of hippocampal LFS and HFS, applied at two or four sites in fully kindled rats.
  
  
  METHODS
  Rats were kindled through a hippocampal tetrode until the fully kindled state. Animals with, stable afterdischarge (AD) threshold were randomly assigned to 5 groups; stimulation at 1Hz (LFS) or, 130Hz (HFS) was continuously applied for 7 days at 2 or 4 intrahippocampal sites; a control, group received no stimulation. Four-contact stimulation was performed in a rotating fashion. Stimulation effects on AD threshold, AD duration and behavioral seizures were assessed.
  
  
  RESULTS
  Four-contact LFS consistently increased AD threshold for a period of 2 days to 2 weeks, whereas 4-contact HFS significantly decreased AD duration 24hours following the stimulation period. No significant AD modification was observed with either 2-contact stimulation paradigms. No, behavioral alteration occurred in any group.
  
  
  CONCLUSIONS
  These findings suggest that effects of hippocampal stimulation depend on frequency and topography of stimulus application. LFS and HFS had anti-epileptic effect on afterdischarges when applied in a rotating pattern. This supports concepts on patterned stimulation to result in desynchronization and anti-kindling effects.
authors.affiliation: Epilepsy Center, University Hospital Freiburg, Breisacherstrasse 64, 79106 Freiburg, Germany; Department of Stereotaxic Neurosurgery, University Hospital Freiburg, University of Freiburg, Breisacherstrasse 64, 79106 Freiburg, Germany; Department of Neurosurgery, Hospital de Clinicas, Federal University of Paraná, R: General Carneiro 181, 80060-900 Curitiba, Paraná, Brazil. Electronic address: joacir.cordeiro@uniklinik-freiburg.de.
authors.forename: Joacir G
authors.initials: JG
authors.lastname: Cordeiro
authors.forename: Karin H
authors.initials: KH
authors.lastname: Somerlik
authors.forename: Karina K
authors.initials: KK
authors.lastname: Cordeiro
authors.forename: Ad
authors.initials: A
authors.lastname: Aertsen
authors.forename: João C
authors.initials: JC
authors.lastname: Araújo
authors.forename: Andreas
authors.initials: A
authors.lastname: Schulze-Bonhage
mesh_terms: D000818:Animals; D004558:Electric Stimulation / Q000009:adverse effects / Q000379:methods; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D007696:Kindling, Neurologic / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time; D012640:Seizures / Q000503:physiopathology
keywords: High-frequency brain stimulation; Hippocampal stimulation; Hippocampus; Kindling; Low-frequency brain stimulation; Multi-site stimulation