Pathological and physiological high-frequency oscillations in focal human epilepsy

Andrew Matsumoto, Benjamin H. Brinkmann, S. Matthew Stead, Joseph Matsumoto, Michal T. Kucewicz, W. Richard Marsh, Frederic Meyer, Gregory Worrell

Research output: Contribution to journalArticlepeer-review

157 Scopus citations


High-frequency oscillations (HFO; gamma: 40-100 Hz, ripples: 100-200 Hz, and fast ripples: 250-500 Hz) have been widely studied in health and disease. These phenomena may serve as biomarkers for epileptic brain; however, a means of differentiating between pathological and normal physiological HFO is essential. We categorized task-induced physiological HFO during periods of HFO induced by a visual or motor task by measuring frequency, duration, and spectral amplitude of each event in single trial time-frequency spectra and compared them to pathological HFO similarly measured. Pathological HFO had higher mean spectral amplitude, longer mean duration, and lower mean frequency than physiological-induced HFO. In individual patients, support vector machine analysis correctly classified pathological HFO with sensitivities ranging from 70-98% and specificities >90% in all but one patient. In this patient, infrequent high-amplitude HFO were observed in the motor cortex just before movement onset in the motor task. This finding raises the possibility that in epileptic brain physiological- induced gamma can assume higher spectral amplitudes similar to those seen in pathologic HFO. This method if automated and validated could provide a step towards differentiating physiological HFO from pathological HFO and improving localization of epileptogenic brain.

Original languageEnglish (US)
Pages (from-to)1958-1964
Number of pages7
JournalJournal of neurophysiology
Issue number8
StatePublished - Oct 2013


  • Epilepsy
  • Gamma oscillations
  • High-frequency oscillations


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