Detection of nonlinear interactions of eeg alpha waves in the brain by a new coherence measure and its application to epilepsy and anti-epileptic drug therapy

David Sherman, Ning Zhang, Shikha Garg, Nitish V. Thakor, Marek A. Mirski, Mirinda Anderson White, Melvin J. Hinich

Research output: Contribution to journalArticle


EEG and field potential rhythms established in the cortex and thalamus may accommodate the propagation of seizures. This article describes the interaction between thalamus and cortex during pentylenetetrazol (PTZ) seizures in rats with and without prior treatment with ethosuximide (ESM), a well-known antiepileptic drug (AED) that raises the threshold for seizures, was given before PTZ. The AED was given before PTZ convulsant administration. We track this thalamo-cortical association with a novel measure we have called the cross-bicoherence gain, or BISCOH. This quantity allows us to measure the spectral coherence in a purely higher order spectralmethodology. BISCOH is able to track the formation of nonlinearities at specific frequencies in the recorded EEG. BISCOH showed a strong increase in low alpha wave harmonic generationat 10 and 12.5 Hz after ESM treatment (p < 0.02 and p < 0.007, respectively). Conventional coherence failed to show distinctive and significant changes in thalamo-cortical coupling after ESM treatment at those frequencies and instead showed changes at 5 Hz. This rise in cortical rhythms is evidence of harmonic generation or new frequency formation in the thalamo-cortical system withAED therapy. BISCOH could become a powerful tool in unraveling changes in coherence due to neuroelectric modulation resulting from drug treatment or electrical stimulation.

Original languageEnglish (US)
Pages (from-to)115-126
Number of pages12
JournalInternational journal of neural systems
Issue number2
StatePublished - Apr 1 2011



  • AED
  • Higher order spectral analysis
  • bicoherence
  • coherence
  • ethosuximide
  • thalamocortical pathways anterior thalamus

ASJC Scopus subject areas

  • Computer Networks and Communications

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