title: A simulation study of the error in dipole source localization for EEG spikes with a realistic head model.
abstract: OBJECTIVE
  We tried to determine the error range of dipole modeling for EEG spikes originating from various clinically important sources by a simulation study employing a realistic head model. The computed error range was also compared with the degree of disturbance of dipole modeling caused by adding background activity to the spike.
  
  
  METHODS
  The scalp fields generated by temporal, frontal and rolandic epileptic sources with spatial extent were simulated, and the corresponding 3-dimensional maps of residual variance (RV) were built by computing the RV for a single dipole at each point on a fine imaginary grid in the brain. Single dipole modeling was also performed for the simulated scalp fields after adding real background activity.
  
  
  RESULTS
  The brain volume corresponding to a small RV was compact for the frontal sources and the lateral and baso-mesial temporal sources, and large for the anterior and baso-lateral temporal sources. The distribution of dipoles estimated for spikes contaminated with background corresponded to that of the volume of small RV and to spike-amplitude. Estimates were improved by employing inferior temporal electrodes.
  
  
  CONCLUSIONS
  When evaluating dipole models of epileptic spikes, error ranges can be estimated and they vary considerably from region to region.
  
  
  CONCLUSIONS
  This study illustrates the variability of the error in dipole modeling of epileptic spikes. This variability is important when considering the clinical interpretation of modeling results.
authors.affiliation: Department of Child Neurology, Okayama University Graduate School of Medicine and Dentistry, 5-1 Shikatacho 2-chome, 700-8558, Okayama, Japan. k_koba@md.okayama-u.ac.jp
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Harumi
authors.initials: H
authors.lastname: Yoshinaga
authors.forename: Makio
authors.initials: M
authors.lastname: Oka
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ohtsuka
authors.forename: Jean
authors.initials: J
authors.lastname: Gotman
mesh_terms: D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D003198:Computer Simulation; D004567:Electrodes, Implanted; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D015203:Reproducibility of Results; D012535:Scalp; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013269:Stochastic Processes