May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Comparisons Between ERG and Behaviorally Determined CFF in a Rodent Model of Retinal Degeneration
Author Affiliations & Notes
  • G. R. Rubin
    Vision Science, Univ of Alabama Birmingham, Birmingham, Alabama
  • M. S. Loop
    Vision Science, Univ of Alabama Birmingham, Birmingham, Alabama
  • T. W. Kraft
    Vision Science, Univ of Alabama Birmingham, Birmingham, Alabama
  • Footnotes
    Commercial Relationships  G.R. Rubin, None; M.S. Loop, None; T.W. Kraft, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 2844. doi:
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      G. R. Rubin, M. S. Loop, T. W. Kraft; Comparisons Between ERG and Behaviorally Determined CFF in a Rodent Model of Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2844.

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

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Abstract

Purpose: : The full-field corneal ERG is frequently used to estimate rod- or cone-driven function in rodent models of retinal degeneration. However, the relationship between ERG response amplitudes and visually guided behavior has been little studied for this model. A longitudinal comparison of ERG to behavioral responses in a light-damage model of retinal degeneration allows us to better understand the functional implications of electrophysiological changes.

Methods: : All animals were handled according to the principles of the ARVO Statement for the Use of Animals in Vision Research. Flicker-ERG and behavioral responses to flicker were used to determine the critical flicker frequency (CFF) of Sprague-Daly albino rats under both scotopic and photopic conditions. Behavioral CFF was determined by two alternative forced choice psychophysical testing in a water maze. Dark- and light-adapted flash ERG b-waves were also measured. Data were collected before and after a 10-day period of low-intensity (280 lux) light-damage that was calibrated to decrease the outer nuclear layer by 50%. Control animals underwent sham light damage, but were maintained under regular cyclic lighting.

Results: : Dark adapted ERG flash responses were reduced by about 50% while CFF determined by flicker-ERG under scotopic conditions was only about 15% lower than control animals on R6, 6 days after light-damage. Behavioral CFF measured under scotopic and photopic conditions was reduced about 15%. Neither the photopic flicker ERG nor the light-adapted flash ERG were significantly different from controls at R6. All CFF values fully recovered by R20, 20 days after light damage. Dark-adapted flash ERG also recovered by R20.

Conclusions: : Flash ERG b-wave amplitudes were severely reduced after light damage in contrast to CFF as measured by ERG or behavior. While reduction of b-wave amplitude mirrors rod loss initially, the relative maintenance of a near threshold flicker signal suggests that different mechanisms are responsible for meditating these separate functions. The recovery of b-wave and flicker sensitivity reveals a plasticity of retinal circuits following injury. These positive changes may be clinically meaningful.

Keywords: temporal vision • electroretinography: non-clinical • degenerations/dystrophies 
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