title: Optical monitoring of neuronal activity during spontaneous sharp waves in chronically epileptic human neocortical tissue.
abstract: Functional changes in neuronal circuitry reflected in spontaneously occurring synchronous sharp field potentials (SSFP) have been reported to occur in human brain suffering from chronic epileptogenicity but not in primary nonepileptic tissue from peritumoral resectates. Voltage sensitive dyes and fast imaging were used to visualize spontaneously occurring rhythmic depolarizations correlated to SSFP in chronically epileptic human neocortical slices obtained during epilepsy surgery. Localized and spatially inhomogeneous neuronal depolarizations were found to underlie spontaneous SSFP, which remained unchanged and spatially restricted to foci <750 micrometer diam even under epileptogenic (low-Mg(2+)) conditions. In cases where ictaform paroxysmal activity occurred in low-Mg(2+) medium, neuronal depolarizations were wide-spread but still spatially inhomogeneous, and the events were preferentially initiated at distinct foci. The findings suggest that small neuronal networks are able to establish and maintain synchronous rhythmic and epileptiform activity.
authors.affiliation: Institut für Physiologie, Westfälische Wilhelms-Universität, 48149 Münster, Germany. kohling@uni-muenster.de
authors.forename: R
authors.initials: R
authors.lastname: Köhling
authors.forename: J M
authors.initials: JM
authors.lastname: Höhling
authors.forename: H
authors.initials: H
authors.lastname: Straub
authors.forename: D
authors.initials: D
authors.lastname: Kuhlmann
authors.forename: U
authors.initials: U
authors.lastname: Kuhnt
authors.forename: I
authors.initials: I
authors.lastname: Tuxhorn
authors.forename: A
authors.initials: A
authors.lastname: Ebner
authors.forename: P
authors.initials: P
authors.lastname: Wolf
authors.forename: H W
authors.initials: HW
authors.lastname: Pannek
authors.forename: A
authors.initials: A
authors.lastname: Gorji
authors.forename: E J
authors.initials: EJ
authors.lastname: Speckmann
mesh_terms: D000200:Action Potentials; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D008274:Magnesium / Q000008:administration & dosage / Q000494:pharmacology; D019579:Neocortex / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology; D009474:Neurons / Q000502:physiology*; D055095:Optics and Photonics; D010507:Periodicity
chemical_list: D008274:Magnesium