Paradox lost? Exploring the role of alpha oscillations during externally vs. internally directed attention and the implications for idling and inhibition hypotheses

Nicholas R. Cooper, Rodney J. Croft, Samuel J.J. Dominey, Adrian P. Burgess, John H. Gruzelier

Research output: Contribution to journalArticle

Abstract

Although slow waves of the electroencephalogram (EEG) have been associated with attentional processes, the functional significance of the alpha component in the EEG (8.1–12 Hz) remains uncertain. Conventionally, synchronisation in the alpha frequency range is taken to be a marker of cognitive inactivity, i.e. ‘cortical idling’. However, it has been suggested that alpha may index the active inhibition of sensory information during internally directed attentional tasks such as mental imagery. More recently, this idea has been amended to encompass the notion of alpha synchronisation as a means of inhibition of non-task relevant cortical areas irrespective of the direction of attention. Here we test the adequacy of the one idling and two inhibition hypotheses about alpha. In two experiments we investigated the relation between alpha and internally vs. externally directed attention using mental imagery vs. sensory-intake paradigms. Results from both experiments showed a clear relationship between alpha and both attentional factors and increased task demands. At various scalp sites alpha amplitudes were greater during internally directed attention and during increased load, results incompatible with alpha reflecting cortical idling and more in keeping with suggestions of active inhibition necessary for internally driven mental operations.
Original languageEnglish
Pages (from-to)65-74
Number of pages10
JournalInternational Journal of Psychophysiology
Volume47
Issue number1
Early online date13 Nov 2002
DOIs
Publication statusPublished - Jan 2003

Keywords

  • electroencephalogram
  • attention
  • internal attention
  • alpha
  • mental imagery
  • oscillations
  • top–down processing
  • inhibition

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