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Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function.

Publication ,  Journal Article
Chu, PHW; Chan, HHL; Ng, Y-F; Brown, B; Siu, AW; Beale, BA; Gilger, BC; Wong, F
Published in: Vision Res
July 2008

PURPOSE: The aim of this study was to obtain a better understanding of the cellular contributions to the porcine global flash mfERG by using a pharmacologic dissection method, together with the method using variation of stimulus contrast which has been used to demonstrate mfERG changes in human glaucoma. METHODS: Global flash mfERGs with different stimulus-contrast settings (99%, 65%, 49% or 29%) were recorded from 14 eyes of ten 6-week-old Yorkshire pigs in control conditions and after suppression of inner retinal responses with inhalation of isoflurance (ISO), and injections of tetrodotoxin (TTX) and N-methyl-d-aspartic acid (NMDA). ON- and OFF-pathway responses were isolated by injection of 2-amino-4-phosphonobutyric acid (APB) and cis-2,3-piperidinedicarboylic acid (PDA). RESULTS: The porcine global flash mfERG consisted of an early direct component (DC) and a late induced component (IC). ISO and TTX removed inner retinal contributions to the IC; NMDA application further abolished the oscillatory wavelets in the DC and removed the residual IC waveform. The inner retina contributed regular oscillation-like wavelets (W1, W2 and W3) to the DC and shaped the IC. After removing the inner retinal contributions, the porcine global flash mfERG waveform becomes comparable to that obtained with conventional mfERG stimulation. The remaining waveform (smoothed DC) was mainly contributed by the ON- and OFF-bipolar cells as revealed after APB or PDA injection. Photoreceptors contributed a small signal to the leading edge of N1. The characteristic of contrast response function of DC was demonstrated to be contributed by the inner retinal oscillation-like wavelets. CONCLUSION: We believe that the DC of the porcine global flash mfERG is mainly composed of contributions from photoreceptors, and ON- and OFF-bipolar cells, where inner retinal activity partially shaped the DC with superimposed regular wavelets. However, the IC is dominated by inner retinal activity. The contrast response functions of DC consisted of both outer retinal response and oscillation-like wavelets of the inner retinal response. Both contain different characteristics during contrast modulation of the stimulus, where the changes of W2 of the inner retinal response seem independent of contrast modulation. The DC contrast response feature depends mainly on the relative contribution of inner retinal activities; the loss of inner retinal cells may alter the DC contrast response function, making it tend toward linearity.

Duke Scholars

Published In

Vision Res

DOI

ISSN

0042-6989

Publication Date

July 2008

Volume

48

Issue

16

Start / End Page

1726 / 1734

Location

England

Related Subject Headings

  • Sus scrofa
  • Retina
  • Photic Stimulation
  • Glaucoma
  • Experimental Psychology
  • Electroretinography
  • Contrast Sensitivity
  • Animals
  • 3212 Ophthalmology and optometry
  • 17 Psychology and Cognitive Sciences
 

Citation

APA
Chicago
ICMJE
MLA
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Chu, P. H. W., Chan, H. H. L., Ng, Y.-F., Brown, B., Siu, A. W., Beale, B. A., … Wong, F. (2008). Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function. Vision Res, 48(16), 1726–1734. https://doi.org/10.1016/j.visres.2008.05.006
Chu, Patrick H. W., Henry H. L. Chan, Yiu-Fai Ng, Brian Brown, Andrew W. Siu, Brady A. Beale, Brian C. Gilger, and Fulton Wong. “Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function.Vision Res 48, no. 16 (July 2008): 1726–34. https://doi.org/10.1016/j.visres.2008.05.006.
Chu PHW, Chan HHL, Ng Y-F, Brown B, Siu AW, Beale BA, et al. Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function. Vision Res. 2008 Jul;48(16):1726–34.
Chu, Patrick H. W., et al. “Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function.Vision Res, vol. 48, no. 16, July 2008, pp. 1726–34. Pubmed, doi:10.1016/j.visres.2008.05.006.
Chu PHW, Chan HHL, Ng Y-F, Brown B, Siu AW, Beale BA, Gilger BC, Wong F. Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function. Vision Res. 2008 Jul;48(16):1726–1734.
Journal cover image

Published In

Vision Res

DOI

ISSN

0042-6989

Publication Date

July 2008

Volume

48

Issue

16

Start / End Page

1726 / 1734

Location

England

Related Subject Headings

  • Sus scrofa
  • Retina
  • Photic Stimulation
  • Glaucoma
  • Experimental Psychology
  • Electroretinography
  • Contrast Sensitivity
  • Animals
  • 3212 Ophthalmology and optometry
  • 17 Psychology and Cognitive Sciences