title: A nonsynaptic mechanism underlying interictal discharges in human epileptic neocortex.
abstract: Very fast oscillations (VFOs, >80 Hz) are important for physiological brain processes and, in excess, with certain epilepsies. Putative mechanisms for VFO include interneuron spiking and network activity in coupled pyramidal cell axons. It is not known whether either, or both, of these apply in pathophysiological conditions. Spontaneously occurring interictal discharges occur in human tissue in vitro, resected from neocortical epileptic foci. VFO associated with these discharges was manifest in both field potential and, with phase delay, in excitatory synaptic inputs to fast spiking interneurons. Recruitment of somatic pyramidal cell and interneuron spiking was low, with no correlation between VFO power and synaptic inputs to principal cells. Reducing synaptic inhibition failed to affect VFO occurrence, but they were abolished by reduced gap junction conductance. These data suggest a lack of a causal role for interneurons, and favor a nonsynaptic pyramidal cell network origin for VFO in epileptic human neocortex.
authors: Institute of Neuroscience, The Medical School, Framlington Place, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK.
authors: Anita K
authors: AK
authors: Roopun
authors: Jennifer D
authors: JD
authors: Simonotto
authors: Michelle L
authors: ML
authors: Pierce
authors: Alistair
authors: A
authors: Jenkins
authors: Claire
authors: C
authors: Nicholson
authors: Ian S
authors: IS
authors: Schofield
authors: Roger G
authors: RG
authors: Whittaker
authors: Marcus
authors: M
authors: Kaiser
authors: Miles A
authors: MA
authors: Whittington
authors: Roger D
authors: RD
authors: Traub
authors: Mark O
authors: MO
authors: Cunningham
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography; D004594:Electrophysiology; D004827:Epilepsy / Q000503:physiopathology*; D018756:GABA Antagonists / Q000494:pharmacology; D006801:Humans; D007395:Interneurons / Q000166:cytology / Q000502:physiology; D008875:Middle Aged; D019579:Neocortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D011724:Pyridazines / Q000494:pharmacology; D009435:Synaptic Transmission / Q000502:physiology; D013702:Temporal Lobe / Q000166:cytology / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D055815:Young Adult
chemical_list: D018756:GABA Antagonists; D011724:Pyridazines; C049853:gabazine