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Existing models of the primate photopic electroretinogram (ERG) attribute the light-adapted b-wave to activity of depolarizing bipolar cells (DBCs), mediated through a release of potassium that is monitored by Müller cells. However, possible ERG contributions from OFF-bipolar cells (HBCs) and horizontal cells (HzCs) have not been explored. We examined the(More)
Visual thresholds of mice for the detection of small, brief targets were measured with a novel behavioral methodology in the dark and in the presence of adapting lights spanning ∼8 log(10) units of intensity. To help dissect the contributions of rod and cone pathways, both wild-type mice and mice lacking rod (Gnat1(-/-)) or cone (Gnat2(cpfl3)) function were(More)
1. Two rod-driven electroretinogram (ERG) components were recorded to monitor scotopic retinal signals during experimental manipulation of dopamine and gamma-aminobutyric acid (GABA) in normal cat eyes and in eyes pretreated with 6-hydroxydopamine (6-OHDA). The scotopic threshold response (STR) was elicited near absolute threshold to monitor signals(More)
Corneal electroretinograms (ERGs) were recorded from anesthetized cats under scotopic conditions. We examined whether the scotopic threshold response (STR) of the ERG could be functionally distinguished from scotopic PII and a-wave using intravitreal application of neuroactive agents. We found that neurotransmitters with active sites on third order neurons(More)
The goal of the present study was to relate the dark and light-adapted flash sensitivity of the scotopic threshold response (STR) and rod b-wave of the electroretinogram (ERG) to behaviorally measured rod increment threshold responses. Small amplitudes of the dark-adapted STR and b-wave, the latter after application of NMDA, were found to increase in(More)
PURPOSE To test the hypothesis that Regulator of G-protein Signaling 9 (RGS9-1) is necessary for the normal inactivation of retinal cones. METHODS Mice having the gene RGS9-1 inactivated in both alleles (RGS9-1 -/-) were tested between the ages 8-10 weeks with electroretinographic (ERG) protocols that isolate cone-driven responses. Immunohistochemistry(More)
We studied the off-response of the rat ERG evoked with long duration, mesopic stimuli during light and dark adaptation, and after intravitreal injection of aspartate and (+/-)-cis-piperidine-2,3-dicarboxylic acid (PDA). At stimulus offset, the dark-adapted ERG always showed a rapid negative deflection followed by a positive deflection after which the(More)
A human rhodopsin mutation, Gly-90-->Asp (Gly90Asp), cosegregated with an unusual trait of congenital nightblindness in 22 at-risk members of a large autosomal dominant kindred. Although rhodopsin mutations typically are associated with retinal degeneration, Gly90Asp-affected subjects up to age 33 did not show clinical retinal changes. Absolute threshold(More)
The influence of annular fields on sensitivity to sinusoidal flicker was assessed in the dark adapted parafoveal retina. Test stimuli were 2 degrees 20' in diameter; annuli had a 2 degrees 20' inner and 7 degrees 30' outer diameter. Rod flicker was studied with a "green" stimulus too dim to influence cones. Selective cone flicker was obtained using red and(More)
1. The influences of short-term visual adaptation of either rods or cones upon cone-mediated grating visibility were compared with their influences upon detection threshold in both the fovea and parafoveal retina. Short-term visual adaptation was induced by 20 deg diameter adapting fields (AFs) generally of 500 ms duration. The AF was either -0.5 log td in(More)