title: Electroencephalographic dipole source modeling of frontal intermittent rhythmic delta activity.
abstract: BACKGROUND
  Frontal intermittent rhythmic delta activity (FIRDA) on electroencephalography (EEG) consists of a run of rhythmic delta waves with frontal predominance. Although FIRDA is a relatively common abnormal EEG finding, the underlying mechanisms that produce FIRDA remain unclear. The aim of this study was to investigate the cortical source of FIRDA using dipole source modeling.
  
  
  METHODS
  We selected EEG epochs, including typical FIRDAs, from EEG recordings obtained using 25 scalp electrodes on 5 subjects. We averaged these epochs by arranging the negative peaks of the delta waves at the Fp electrodes and estimated dipoles for nine averaged waveforms.
  
  
  RESULTS
  Averaged waveforms were explained by a single-dipole model in seven FIRDAs and by a two-dipole model in the remaining two FIRDAs with high reliability. Estimated dipoles had a radial orientation with respect to the frontal pole and were located in the medial frontal region. The anterior cingulate cortex was the most common dipole location.
  
  
  CONCLUSIONS
  This is the first study to approach the fundamental FIRDA mechanism by dipole source modeling and to clarify that FIRDA may be generated from the medial frontal region, particularly from the anterior cingulate cortex.
authors.affiliation: Department of Psychiatry, Division of Neuroscience, Institute of Medical Science, Mie University Graduate School of Medicine, Tsu, Japan. motomura@clin.medic.mie-u.ac.jp
authors.forename: Eishi
authors.initials: E
authors.lastname: Motomura
authors.forename: Koji
authors.initials: K
authors.lastname: Inui
authors.forename: Keiko
authors.initials: K
authors.lastname: Ohoyama
authors.forename: Yukika
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Maeda
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Matsushima
authors.forename: Kengo
authors.initials: K
authors.lastname: Ushiro
authors.forename: Dai
authors.initials: D
authors.lastname: Suzuki
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kakigi
authors.forename: Motohiro
authors.initials: M
authors.lastname: Okada
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D003700:Delta Rhythm / Q000502:physiology*; D004566:Electrodes; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015203:Reproducibility of Results; D055815:Young Adult