title: Spatiotemporal dynamics and functional correlates of evoked neural oscillations with different spectral powers in human visual cortex.
abstract: OBJECTIVE
  To investigate spatiotemporal characteristics and functional correlates of evoked oscillations (EOs) at different frequency bands in human visual cortex.
  
  
  METHODS
  Flash visual evoked potentials (FVEPs) were recorded from 11 epilepsy patients with intracranial electrodes placed over the occipital and adjacent cortices. Spatiotemporal characteristics of spectral powers and correlation with various visual responses elicited by electrical cortical stimulations were analyzed in the same electrodes.
  
  
  RESULTS
  High γ (60-150 Hz) EOs were first recorded in the cuneus and lingual gyri around the calcarine sulcus. Low γ (30-60 Hz) EOs appeared also in the mesial occipital cortex slightly later and lasted longer than high γ EGOs. In contrast, lower frequency (LF) <30 Hz EOs were recorded more diffusely from occipital surfaces with delayed onset and longer duration. High γ EOs were predominantly associated with simple form visual responses, whereas low γ and LF EOs were with intermediate form and LF EOs with complex form responses.
  
  
  CONCLUSIONS
  FVEP spectral power analysis directly recorded from human visual cortex showed distinct spatiotemporal distributions in high and low γ, or LF bands that have different functional correlates.
  
  
  CONCLUSIONS
  Phase-locked EOs in these frequency bands may have special neuroanatomical and functional organization during early visual processing.
authors.affiliation: Department of Neurology, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, Republic of Korea.
authors.forename: Song E
authors.initials: SE
authors.lastname: Kim
authors.forename: Won Sup
authors.initials: WS
authors.lastname: Kim
authors.forename: Byung Gon
authors.initials: BG
authors.lastname: Kim
authors.forename: Dongil
authors.initials: D
authors.lastname: Chung
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Jeong
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Lee
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Tae
authors.forename: Seung Bong
authors.initials: SB
authors.lastname: Hong
authors.forename: Hyang Woon
authors.initials: HW
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002648:Child; D003626:Data Display; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009778:Occipital Lobe / Q000502:physiology; D062211:Spatio-Temporal Analysis; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Cortical localization; Evoked neural oscillations; Functional mapping; Intracranial electrode; Visual evoked potential (VEP)