title: Interictal high-frequency oscillations generated by seizure onset and eloquent areas may be differentially coupled with different slow waves.
abstract: High-frequency oscillations (HFOs) can be spontaneously generated by seizure-onset and functionally-important areas. We determined if consideration of the spectral frequency bands of coupled slow-waves could distinguish between epileptogenic and physiological HFOs.
  
  
  
  We studied a consecutive series of 13 children with focal epilepsy who underwent extraoperative electrocorticography. We measured the occurrence rate of HFOs during slow-wave sleep at each electrode site. We subsequently determined the performance of HFO rate for localization of seizure-onset sites and undesirable detection of nonepileptic sensorimotor-visual sites defined by neurostimulation. We likewise determined the predictive performance of modulation index: MI(XHz)&(YHz), reflecting the strength of coupling between amplitude of HFOsXHz and phase of slow-waveYHz. The predictive accuracy was quantified using the area under the curve (AUC) on receiver-operating characteristics analysis.
  
  
  
  Increase in HFO rate localized seizure-onset sites (AUC⩾0.72; p<0.001), but also undesirably detected nonepileptic sensorimotor-visual sites (AUC⩾0.58; p<0.001). Increase in MI(HFOs)&(3-4Hz) also detected both seizure-onset (AUC⩾0.74; p<0.001) and nonepileptic sensorimotor-visual sites (AUC⩾0.59; p<0.001). Increase in subtraction-MIHFOs [defined as subtraction of MI(HFOs)&(0.5-1Hz) from MI(HFOs)&(3-4Hz)] localized seizure-onset sites (AUC⩾0.71; p<0.001), but rather avoided detection of nonepileptic sensorimotor-visual sites (AUC⩽0.42; p<0.001).
  
  
  
  Our data suggest that epileptogenic HFOs may be coupled with slow-wave3-4Hz more preferentially than slow-wave0.5-1Hz, whereas physiologic HFOs with slow-wave0.5-1Hz more preferentially than slow-wave3-4Hz during slow-wave sleep.
  
  
  
  Further studies in larger samples are warranted to determine if consideration of the spectral frequency bands of slow-waves coupled with HFOs can positively contribute to presurgical evaluation of patients with focal epilepsy.
authors.affiliation: Pediatrics, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nonoda
authors.affiliation: Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA.
authors.forename: Makoto
authors.initials: M
authors.lastname: Miyakoshi
authors.affiliation: Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Ojeda
authors.affiliation: Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Makeig
authors.affiliation: Pediatrics, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA; Neurology, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Csaba
authors.initials: C
authors.lastname: Juhász
authors.affiliation: Neurosurgery, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Sood
authors.affiliation: Pediatrics, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA; Neurology, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA. Electronic address: eishi@pet.wayne.edu.
authors.forename: Eishi
authors.initials: E
authors.lastname: Asano
mesh_terms: D000293:Adolescent; D001931:Brain Mapping; D058256:Brain Waves; D002648:Child; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D066191:Sensorimotor Cortex / Q000502:physiology / Q000503:physiopathology*; D012890:Sleep
keywords: EEGLAB; High-gamma activity; Intracranial electrocorticography (ECoG) recording; Neurophysiology; Pathological and physiological high-frequency oscillations (HFOs); Pediatric epilepsy surgery; Phase–amplitude coupling; Receiver-operating characteristics (ROC) curve; Ripples; Subdural electroencephalography (EEG); Subtraction modulation index co-registered to MRI (SMICOM)