September 2011
Volume 11, Issue 11
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2011
Who's controlling the brakes? Pulsed inhibitory alpha EEG is linked to preparatory activity in the fronto-parietal network measured concurrently with the event-related optical signal (EROS)
Author Affiliations
  • Kyle E. Mathewson
    Beckman Intitute and Department of Psychology, University of Illinois at Urbana-Champaign, USA
  • Diane M. Beck
    Beckman Intitute and Department of Psychology, University of Illinois at Urbana-Champaign, USA
  • Tony Ro
    Department of Psychology, The City College of the City University of New York, USA
  • Monica Fabiani
    Beckman Intitute and Department of Psychology, University of Illinois at Urbana-Champaign, USA
  • Gabriele Gratton
    Beckman Intitute and Department of Psychology, University of Illinois at Urbana-Champaign, USA
Journal of Vision September 2011, Vol.11, 195. doi:10.1167/11.11.195
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      Kyle E. Mathewson, Diane M. Beck, Tony Ro, Monica Fabiani, Gabriele Gratton; Who's controlling the brakes? Pulsed inhibitory alpha EEG is linked to preparatory activity in the fronto-parietal network measured concurrently with the event-related optical signal (EROS). Journal of Vision 2011;11(11):195. doi: 10.1167/11.11.195.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Alpha oscillations have an inhibitory influence on visual processing and fluctuate with both sustained and directed attention. We have proposed a role for these 8–12 Hz oscillations as a pulsed inhibition of ongoing brain activity, given that alpha’s inhibitory influence fluctuates as a function of its phase. An important prediction of this theory is that top-down signals from the fronto-parietal network elicit changes in this pulsed inhibitory alpha activity over visual cortex. We tested this prediction by measuring preparatory neural activity in the fronto-parietal network using the event-related optical signal (EROS), which affords high temporal and spatial resolution, while concurrently measuring oscillations in alpha activity over visual areas with the electroencephalogram (EEG). We tested the influence of this brain activity on visual awareness by having subjects perform a metacontrast masking task. Extending our previous findings, both EEG and EROS showed oscillations in parietal areas in the period before the target presentation, with the phase of these oscillations predicting subsequent target detection. We also replicated previous findings showing that decreases in alpha power predict target detection, verifying their inhibitory role in visual processing. The pre-target EROS activity in right pre-frontal and parietal areas also predicted subsequent target detection. Crucially, these increased differences in EROS activity between detected and undetected targets correlated negatively with EEG alpha power across subjects. Furthermore, sorting the EROS data based on single trial EEG alpha power revealed that EROS frontal activity was associated with decreased alpha power, whereas subsequent parietal activity was associated with increases in alpha power. Together, these results provide support for our theory that alpha oscillations represent pulsed inhibition of ongoing activity. These data further suggest that these oscillations may be controlled by top-down influences from the fronto-parietal attention network.

Supported by a Natural Science and Engineering Research Council of Canada (NSERC) fellowship to Kyle E. Mathewson and grant R01MH080182 from NIMH to Gabriele Gratton. 
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