Mechanisms of selective inhibition in visual spatial attention are indexed by α-band EEG synchronization

Authors

  • Tonia A. Rihs,

    1. Functional Brain Mapping Laboratory, Department of Neurology, University Hospital Geneva, 24, Rue Micheli du Crest, CH-1211 Geneva 14, Switzerland
    2. Department of Fundamental Neuroscience, University Medical School, Geneva, Switzerland
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  • Christoph M. Michel,

    1. Functional Brain Mapping Laboratory, Department of Neurology, University Hospital Geneva, 24, Rue Micheli du Crest, CH-1211 Geneva 14, Switzerland
    2. Department of Fundamental Neuroscience, University Medical School, Geneva, Switzerland
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  • Gregor Thut

    1. Functional Brain Mapping Laboratory, Department of Neurology, University Hospital Geneva, 24, Rue Micheli du Crest, CH-1211 Geneva 14, Switzerland
    2. Department of Fundamental Neuroscience, University Medical School, Geneva, Switzerland
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Dr Gregor Thut, 1Functional Brain Mapping Laboratory, as above.
E-mail: gregor.thut@medecine.unige.ch

Abstract

Electroencephalographic studies in humans have demonstrated that orienting of visual attention induces a decrease in oscillatory α-band activity (α-desynchronization) over cortical areas tuned to the attended visual space. This is interpreted as reflecting intentionally enhanced excitability of these areas to facilitate upcoming visual processing. However, the inverse mechanism might also apply. Brain areas that process task-irrelevant space might be actively suppressed by increased α-activity (α-synchronization) to protect against input of distracter information. In the present study, we demonstrate that such suppression mechanisms are highly selective and are taking place even without distracters that need to be ignored. During voluntary orienting of attention, we found α-synchronization to dominate over desynchronization, to be topographically specific for each of eight attention positions, and to occur over areas processing unattended space in a retinotopically organized pattern. This indicates that α-synchronization is an important component of selective attention, serving active suppression of unattended positions during visual spatial orienting.

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