May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
A comparison of posterior cortical gamma in man when saccades are executed to visual targets and without visual targets in the dark.
Author Affiliations & Notes
  • I. Bodis–Wollner
    Dept of Neurology,
    SUNY Downstate, Brooklyn, NY
  • P. Forgacs
    Dept of Neurology,
    SUNY Downstate, Brooklyn, NY
  • H. von Gizycki
    Center for Scientific Computing,
    SUNY Downstate, Brooklyn, NY
  • M. Avitable
    Center for Scientific Computing,
    SUNY Downstate, Brooklyn, NY
  • V. Amassian
    Dept of Physiology and Pharmacology,
    SUNY Downstate, Brooklyn, NY
  • I. Selesnick
    Dept of Electrical Engineering, Polytechnic University, Brooklyn, NY
  • A. Syed
    Dept of Neurology,
    SUNY Downstate, Brooklyn, NY
  • Footnotes
    Commercial Relationships  I. Bodis–Wollner, None; P. Forgacs, None; H. von Gizycki, None; M. Avitable, None; V. Amassian, None; I. Selesnick, None; A. Syed, None.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 2516. doi:
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      I. Bodis–Wollner, P. Forgacs, H. von Gizycki, M. Avitable, V. Amassian, I. Selesnick, A. Syed; A comparison of posterior cortical gamma in man when saccades are executed to visual targets and without visual targets in the dark. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2516.

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

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Abstract

Abstract: : Purpose: To quantify posterior occipital EEG chnages associated with voluntary saccades. Methods: 10 subjects were studied . The EEG was recorded using 13 electrode pairs covering the posterior (parietal, temporal and occipital) cortices. EOG and infrared eye position signals were recorded. Single trial perisaccadic EEG was anlyzed in four time windows (preceding, duringand following) each saccade, The analysis was performed using Continous wavelet transform followed by Hilbert transform. Saccades were executed to visible markers 17.5 degrees from fixation or without markers when the observer was blindfolded. Saccadic accuracy was calibrated using the EOG/ISCAN calibration statistics obtained for each observer.General linear model was used for statistical evaluation. Results: Gamma power was highest in the intrasccadic period.Perisaccadic gamma power was significantly higher in the dark than in the light, over the occipital and posterior parietal recording sites. Conclusions: The powerful intrasccadic modulation of gamma activity (38.4 Hertz) provides evidence that gamma increase is not a corollary of the pre–motor signalling sytem. The fact that it is more prominent when vision is occluded suggests the intrasaccadic gamma is a mechanism for preparation for the locus of new fixation. It remains to be seen whether intrasaccadic gamma represents visuo–spatial shift of attention , as an intrinsic mechanism of the saccadic exploration of the visual space, with or without concurrent visual input.

Keywords: visual cortex • visual search • vision and action 
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