April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Parametric Analysis of the Human ERG to Long Duration Stimuli
Author Affiliations & Notes
  • E. V. Vukmanic
    Psychol & Brain Sci,
    University of Louisville, Louisville, Kentucky
  • P. J. DeMarco
    Psychological and Brain Sciences,
    University of Louisville, Louisville, Kentucky
  • Footnotes
    Commercial Relationships  E.V. Vukmanic, None; P.J. DeMarco, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 1499. doi:
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      E. V. Vukmanic, P. J. DeMarco; Parametric Analysis of the Human ERG to Long Duration Stimuli. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1499.

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

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Purpose: : The flash electroretinogram (ERG) is a retinal evoked potential which reflects contributions from photoreceptors, bipolar cells, and inner-retina networks. The standard stimulus for the ERG is a short duration increment flash, but the morphology of the ERG waveform can be significantly influenced by the duration and polarity of the stimulus. Here we investigate the influence of long-duration positive and negative light stimuli on the morphology, amplitude and latency of the constituent ERG component waveforms.

Methods: : ERG responses were recorded from human subjects using DTL fiber electrodes using standard recording procedures. Stimuli were positive and negative square-wave flashes, and rapid-on and rapid-off sawtooth stimuli, produced by a ganzfeld stimulator. Stimulation was initiated from a standard background luminance of 175 cd/m2. For square wave stimuli, flash duration was varied from 5-250 ms while flash contrast was varied +/- 85%. Mean intensity-response functions were derived for the b-wave and d-wave responses and fit with log-linear curves. Sawtooth stimuli were modulated at 4 Hz from the same mean luminance.

Results: : Flash duration and polarity affects the morphological characteristics of both the b- and d-waves of the ERG. Analysis of the intensity-response functions for these waveforms reveals a steeper slope and larger amplitude for the d-wave response compared to the b-wave response to equal contrast flashes. The initial rise of the d-wave is consistent in time-course and slope to that of the a-wave, suggesting contribution from photoreceptors. Sawtooth stimuli produce ERGs that differ in morphology than ERGs induced by similar duration square-wave stimuli. Fourier analysis reveals distinct temporal frequency components in the ERGs to opposite polarity stimuli.

Conclusions: : Intensity-response and duration-response measurement of the ERG reveal nonlinear summation of activity from ON- and OFF-retinal pathways. The use of opposite polarity stimuli expands the utility of the ERG as an analysis tool for the assessing the function, and integrity, of inner-retinal networks.

Keywords: electroretinography: non-clinical • electrophysiology: non-clinical 

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