Cortical gamma responses: Searching high and low

Nathan E. Crone, Anna Korzeniewska, Piotr J. Franaszczuk

Research output: Contribution to journalReview article

Abstract

In this paper, a brief, preliminary attempt is made to frame a scientific debate about how functional responses at gamma frequencies in electrophysiological recordings (EEG, MEG, ECoG, and LFP) should be classified and interpreted. In general, are all gamma responses the same, or should they be divided into different classes according to criteria such as their spectral characteristics (frequency range and/or shape), their spatial-temporal patterns of occurrence, and/or their responsiveness under different task conditions? In particular, are the responses observed in intracranial EEG at a broad range of "high gamma" frequencies (~. 60-200. Hz) different from gamma responses observed at lower frequencies (~. 30-80. Hz), typically in narrower bands? And if they are different, how should they be interpreted? Does the broad spectral shape of high gamma responses arise from the summation of many different narrow-band oscillations, or does it reflect something completely different? If we are not sure, should we refer to high gamma activity as oscillations? A variety of theories have posited a mechanistic role for gamma activity in cortical function, often assuming narrow-band oscillations. These theories continue to influence the design of experiments and the interpretation of their results. Do these theories apply to all electrophysiological responses at gamma frequencies? Although no definitive answers to these questions are immediately anticipated, this paper will attempt to review the rationale for why they are worth asking and to point to some of the possible answers that have been proposed.

Original languageEnglish (US)
Pages (from-to)9-15
Number of pages7
JournalInternational Journal of Psychophysiology
Volume79
Issue number1
DOIs
StatePublished - Jan 1 2011

    Fingerprint

Keywords

  • ERD/ERS
  • Electrocorticography
  • Electroencephalography
  • Functional mapping
  • Gamma band
  • High gamma
  • Induced responses
  • Oscillations

ASJC Scopus subject areas

  • Neuroscience(all)
  • Neuropsychology and Physiological Psychology
  • Physiology (medical)

Cite this