Contributions to the electroretinogram of currents originating in proximal retina

Laura J. Frishman, Paul A. Sieving, Roy H. Steinberg

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36 Scopus citations


We have investigated responses in proximal retina of the cat that contribute to two kinds of electroretinogram (ERG) recordings: (1) the pattern ERG, a light-adapted response and (2) the threshold and near threshold ERG, a dark-adapted response (Sieving et al., 1986a, 1986b; Sieving & Steinberg, 1985). In intraretinal, extracellular recordings, two negative-going responses were identified that are maximal around the inner plexiform layer, and distinct from PII, which is maximal in distal retina: under light-adapted conditions, a spatially tuned response at light onset and light offset, the “M-wave” (previously described in cold-blooded animals by Karwoski & Proenza (1977, 1980)), and under dark-adapted conditions, the scotopic threshold response, or “STR, ” a response at light onset. The results under dark-adapted conditions are examined in more detail here. The STR is a very sensitive response whose threshold is 1.5-2.0 log units below that of the dc-component of PII and therefore well below the threshold of the a-, b-, and c-waves. It saturates about 2.4 log units below rod saturation. The STR contributes a negative-going potential to the dark-adapted ERG that is dominant near threshold; while PII (dc-component and b-wave) contributes a positive-going potential that is dominant at higher intensities (Sieving et al., 1986b). Investigation of the mechanism of the proximal retinal responses that contribute to the ERG supports a K+-Müller cell hypothesis of their origin.

Original languageEnglish (US)
Pages (from-to)307-315
Number of pages9
JournalVisual Neuroscience
Issue number3
StatePublished - May 1988
Externally publishedYes


  • Cat retina
  • Electroretinogram
  • Muller cell
  • Retina
  • Retinal [K+]0

ASJC Scopus subject areas

  • Physiology
  • Sensory Systems


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