Unsupervised machine-learning classification of electrophysiologically active electrodes during human cognitive task performance.

Journal: Scientific reports
PMID: 31758077

Abstract

Identification of active electrodes that record task-relevant neurophysiological activity is needed for clinical and industrial applications as well as for investigating brain functions. We developed an unsupervised, fully automated approach to classify active electrodes showing event-related intracranial EEG (iEEG) responses from 115 patients performing a free recall verbal memory task. Our approach employed new interpretable metrics that quantify spectral characteristics of the normalized iEEG signal based on power-in-band and synchrony measures. Unsupervised clustering of the metrics identified distinct sets of active electrodes across different subjects. In the total population of 11,869 electrodes, our method achieved 97% sensitivity and 92.9% specificity with the most efficient metric. We validated our results with anatomical localization revealing significantly greater distribution of active electrodes in brain regions that support verbal memory processing. We propose our machine-learning framework for objective and efficient classification and interpretation of electrophysiological signals of brain activities supporting memory and cognition.

Authors

  • Krishnakant V Saboo
    University of Illinois, Dept. of Electrical and Computer Engineering, Urbana-Champaign, IL, USA. ksaboo2@illinois.edu.
  • Yogatheesan Varatharajah
    * Electrical and Computer Engineering, University of Illinois at Urbana-Champaign Urbana, IL 61801, USA.
  • Brent M Berry
    † Department of Neurology and Physiology & Biomedical Engineering, Mayo Clinic Rochester, MN 55905, USA.
  • Vaclav Kremen
    Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, MN, USA.
  • Michael R Sperling
    Department of Neurology, Thomas Jefferson University Hospital.
  • Kathryn A Davis
    Penn Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia, PA 19104; Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104.
  • Barbara C Jobst
    Department of Neurology, Darmouth-Hitchcock Medical Center.
  • Robert E Gross
    Department of Neurosurgery, Emory University, Atlanta, GA 30322, USA.
  • Bradley Lega
  • Sameer A Sheth
  • Gregory A Worrell
    Mayo Systems Electrophysiology Laboratory, Department of Neurology, Mayo Clinic, Rochester, MN, USA.
  • Ravishankar K Iyer
    Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
  • Michal T Kucewicz
    Mayo Clinic, Dept. of Neurology, Rochester, MN, USA. Kucewicz.Michal@mayo.edu.

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