title: The functional organization of human epileptic hippocampus.
abstract: The function and connectivity of human brain is disrupted in epilepsy. We previously reported that the region of epileptic brain generating focal seizures, i.e., the seizure onset zone (SOZ), is functionally isolated from surrounding brain regions in focal neocortical epilepsy. The modulatory effect of behavioral state on the spatial and spectral scales over which the reduced functional connectivity occurs, however, is unclear. Here we use simultaneous sleep staging from scalp EEG with intracranial EEG recordings from medial temporal lobe to investigate how behavioral state modulates the spatial and spectral scales of local field potential synchrony in focal epileptic hippocampus. The local field spectral power and linear correlation between adjacent electrodes provide measures of neuronal population synchrony at different spatial scales, ∼1 and 10 mm, respectively. Our results show increased connectivity inside the SOZ and low connectivity between electrodes in SOZ and outside the SOZ. During slow-wave sleep, we observed decreased connectivity for ripple and fast ripple frequency bands within the SOZ at the 10 mm spatial scale, while the local synchrony remained high at the 1 mm spatial scale. Further study of these phenomena may prove useful for SOZ localization and help understand seizure generation, and the functional deficits seen in epileptic eloquent cortex.
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Institute of Scientific Instruments of the CAS, Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic;
authors.forename: Petr
authors.initials: P
authors.lastname: Klimes
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Department of Computing and Mathematics, FFCLRP, University of São Paulo, Ribeirão Preto SP, Brazil;
authors.forename: Juliano J
authors.initials: JJ
authors.lastname: Duque
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Ben
authors.initials: B
authors.lastname: Brinkmann
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota;
authors.forename: Jamie
authors.initials: J
authors.lastname: Van Gompel
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Matt
authors.initials: M
authors.lastname: Stead
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Mayo Center for Sleep Medicine, Departments of Neurology and Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Erik K
authors.initials: EK
authors.lastname: St Louis
authors.affiliation: Institute of Scientific Instruments of the CAS, Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic;
authors.forename: Josef
authors.initials: J
authors.lastname: Halamek
authors.affiliation: Institute of Scientific Instruments of the CAS, Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic;
authors.forename: Pavel
authors.initials: P
authors.lastname: Jurak
authors.affiliation: Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, Minnesota; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, Minnesota; and worrell.gregory@mayo.edu.
authors.forename: Gregory
authors.initials: G
authors.lastname: Worrell
mesh_terms: D000328:Adult; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology; D013057:Spectrum Analysis; D055815:Young Adult
keywords: behavioral state; connectivity; epilepsy; intracranial EEG; seizure onset zone