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On cross-frequency phase-phase coupling between theta and gamma oscillations in the hippocampus

  1. Robson Scheffer-Teixeira
  2. Adriano BL Tort  Is a corresponding author
  1. Federal University of Rio Grande do Norte, Brazil
Research Article
  • Cited 31
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Cite this article as: eLife 2016;5:e20515 doi: 10.7554/eLife.20515

Abstract

Phase-amplitude coupling between theta and multiple gamma sub-bands is a hallmark of hippocampal activity and believed to take part in information routing. More recently, theta and gamma oscillations were also reported to exhibit phase-phase coupling, or n:m phase-locking, suggesting an important mechanism of neuronal coding that has long received theoretical support. However, by analyzing simulated and actual LFPs, here we question the existence of theta-gamma phase-phase coupling in the rat hippocampus. We show that the quasi-linear phase shifts introduced by filtering lead to spurious coupling levels in both white noise and hippocampal LFPs, which highly depend on epoch length, and that significant coupling may be falsely detected when employing improper surrogate methods. We also show that waveform asymmetry and frequency harmonics may generate artifactual n:m phase-locking. Studies investigating phase-phase coupling should rely on appropriate statistical controls and be aware of confounding factors; otherwise, they could easily fall into analysis pitfalls.

Article and author information

Author details

  1. Robson Scheffer-Teixeira

    Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
    Competing interests
    The authors declare that no competing interests exist.
  2. Adriano BL Tort

    Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
    For correspondence
    tort@neuro.ufrn.br
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9877-7816

Funding

Conselho Nacional de Desenvolvimento Científico e Tecnológico

  • Robson Scheffer-Teixeira
  • Adriano BL Tort

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

  • Robson Scheffer-Teixeira
  • Adriano BL Tort

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All procedures were approved by our local institutional ethics committee (Comissão de Ética no Uso de Animais - CEUA/UFRN, protocol number 060/2011) and were in accordance with the National Institutes of Health guidelines.

Reviewing Editor

  1. Frances K Skinner, University Health Network, Canada

Publication history

  1. Received: August 10, 2016
  2. Accepted: December 5, 2016
  3. Accepted Manuscript published: December 7, 2016 (version 1)
  4. Version of Record published: December 29, 2016 (version 2)

Copyright

© 2016, Scheffer-Teixeira & Tort

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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