title: Emergence of dominant initiation sites for interictal spikes in rat neocortex.
abstract: Neuronal populations with unbalanced inhibition can generate interictal spikes (ISs), where each IS starts from a small initiation site and then spreads activation across a larger area. We used in vivo voltage-sensitive dye imaging to map the initiation site of ISs in rat visual cortex disinhibited by epidural application of bicuculline methiodide. Immediately after the application of bicuculline, the IS initiation sites were widely distributed over the entire disinhibited area. After ∼ 10 min, a small number of sites became "dominant" and initiated the majority of the ISs throughout the course of imaging. Such domination also occurred in cortical slices, which lack long-range connections between the cortex and subcortical structures. This domination of IS initiation sites may allow timing-related plasticity mechanisms to provide a spatial organization where connections projecting outward from the dominant initiation site become strengthened. Understanding the spatiotemporal organization of IS initiation sites may contribute to our understanding of epileptogenesis in its very early stages, because a dominant IS initiation site with strengthened outward connectivity may ultimately develop into a seizure focus.
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia; Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia;
authors.forename: Daniel
authors.initials: D
authors.lastname: Vitantonio
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia;
authors.forename: Weifeng
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Biomedical Engineering, Capital Medical University, Beijing, China;
authors.forename: Xinling
authors.initials: X
authors.lastname: Geng
authors.affiliation: Georgetown University Medical Center, Interdepartmental Program of Neuroscience, Washington, District of Columbia; and.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Wolff
authors.affiliation: Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.
authors.forename: Kentaroh
authors.initials: K
authors.lastname: Takagaki
authors.affiliation: Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia;
authors.forename: Gholam K
authors.initials: GK
authors.lastname: Motamedi
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia; wuj@georgetown.edu.
authors.forename: Jian-young
authors.initials: JY
authors.lastname: Wu
mesh_terms: D000200:Action Potentials; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D003292:Convulsants / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D019579:Neocortex / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition; D051381:Rats; D017207:Rats, Sprague-Dawley; D014793:Visual Cortex / Q000187:drug effects / Q000502:physiology*
chemical_list: D003292:Convulsants; D001640:Bicuculline
keywords: epileptiform focus; interictal spikes; propagating waves; seizure initiation; voltage-sensitive dye imaging