September 2019
Volume 19, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2019
Visual signals removed by opaque contact lens blocks alpha oscillations: Resting state EEG effects
Author Affiliations & Notes
  • Joseph FX DeSouza
    Centre for Vision Research, Psychology, York University
  • Nevena Savija
    Biology, York University
  • Rebecca Barnstaple
    Centre for Vision Research, Psychology, York University
    Dance, York University
Journal of Vision September 2019, Vol.19, 274b. doi:
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      Joseph FX DeSouza, Nevena Savija, Rebecca Barnstaple; Visual signals removed by opaque contact lens blocks alpha oscillations: Resting state EEG effects. Journal of Vision 2019;19(10):274b.

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

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We are interested in quantifying the influence of visual signals in the alpha oscillation when comparing eyes open (EO) and eyes closed (EC) conditions. Alpha rhythms are thought to be generated by reciprocal connections between the thalamus and posterior cortices (visual/parietal), and modulation has been associated with cognitive states including arousal, attention and inhibition. Alpha desynchronization or blocking occurs in EO versus EC conditions. Importantly, alpha oscillations appear to slow/weaken during the aging process in people with Alzheimer’s, Mild Cognitive Impairment and Parkinson’s disease. Methods: We studied alpha changes over a 6-hour period during which data was collected up to six times in 12-subjects (7 female, mean age = 26.25, range = 21–45) during a resting state EEG paradigm with EO/EC; subjects were fitted with opaque contact lenses after the first two sessions. Our aim was to compare across EO and EC in prolonged blindness of normally sighted participants. Between each six-minute rsEEG session, participants additionally underwent a sound localization task in which they were asked to point their heads to 16-speakers equally distributed in front of them in a dark sound attenuated room (Savija et al 2015, Society for Neuroscience). In all, participants experienced 6 sessions: 1 = Light/sighted, 2 = blindfold, 3 = blind, {90 min}, 4 = blind, {180 min}, 5 = Light/ sighted, {+60 min}, and 6 = Light/sighted. Results: At timepoints 3 to 5, which correspond with those in which vision is totally occluded, alpha power decreased in the EC condition, an opposite effect of the historically observed alpha block in EO. At timepoint 6 (5 hours) when the contacts have been removed, there is a residual effect of minimal change in alpha EO/EC. These findings indicate that visual signals exert a high degree of influence in the alpha oscillation, an effect which merits further exploration.

Acknowledgement: NSERC Discovery 

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