Oscillatory brain activity in the canonical alpha-band conceals distinct mechanisms in attention.

Gabriela Cruz*, Maria Melcón, Leonardo Sutandi, J. Matias Palva, Satu Palva, Gregor Thut*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

Brain oscillations in the alpha-band (8-14 Hz) have been linked to specific processes in attention and perception. In particular, decreases in posterior alpha-amplitude are thought to reflect activation of perceptually relevant brain areas for target engagement, while alpha-amplitude increases have been associated with inhibition for distractor suppression. Traditionally, these alpha-changes have been viewed as two facets of the same process. However, recent evidence calls for revisiting this interpretation. Here, we recorded MEG/EEG in 32 participants (19 females) during covert visuospatial attention shifts (spatial cues) and two control conditions (neutral cue, no-attention cue), while tracking fixational eye movements. In disagreement with a single, perceptually relevant alpha-process, we found the typical alpha-modulations contra- and ipsilateral to the attention focus to be triple dissociated in their timing, topography, and spectral features: Ipsilateral alpha-increases occurred early, over occipital sensors, at a high alpha-frequency (10–14 Hz) and were expressed during spatial attention (alpha spatial cue > neutral cue). In contrast, contralateral alpha-decreases occurred later, over parietal sensors, at a lower alpha-frequency (7–10 Hz) and were associated with attention deployment in general (alpha spatial and neutral cue < no-attention cue). Additionally, the lateralized early alpha-increases but not alpha-decreases during spatial attention coincided in time with directionally biased microsaccades. Overall, this suggests that the attention-related early alpha-increases and late alpha-decreases reflect distinct, likely reflexive versus endogenously controlled attention mechanisms. We conclude that there is more than one perceptually relevant posterior alpha-oscillation, which need to be dissociated for a detailed account of their roles in perception and attention.

Original languageEnglish
Article numbere0918242024
JournalJournal of Neuroscience
Volume45
Issue number1
Early online date15 Oct 2024
DOIs
Publication statusPublished - 1 Jan 2025
MoE publication typeA1 Journal article-refereed

Keywords

  • temporal expectation
  • attention
  • alpha-oscillations
  • EEG/MEG
  • visuospatial orienting
  • microsaccades

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