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J.M. Harrison, P.M. Kurian; Oscillatory Potential (OP) and B–Wave Amplitude Changes in the Electroretinogram (ERG) of the Mouse during Light Adaptation . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5693.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the change in amplitude of the low band–pass filtered b–wave and the integrated high band–pass filtered OPs of the ERGs arising in the cone system of the mouse during light adaptation. It is known that the b–wave amplitude of the wide band–pass ERG of the mouse increases during light adaptation, but it has not been determined to what extent the high frequency OPs, prominent in the mouse, superimposed on the unfiltered b–wave contribute to the change in its amplitude during light adaptation. Methods: Mice were dark adapted for 4 hr, prepared for testing under dim red illumination, and exposed to full–field illumination sufficient to desensitize the rod system (2600 scotopic td). Full–field ERGs were produced by flashes with a luminance of 2 cd s m–2 at intervals of 1–3 min during exposure to the background from the onset of light adaptation to a time15 min later. Wide band–pass ERGs (1–1000 Hz) were recorded with silver–bonded nylon fibers from the apical cornea of the right eye of 10 anesthetized (ketamine–xylazine) mice. Off–line, the ERGs produced at 0 and 15 min were processed by a finite impulse response filter to yield low and high band–pass filtered ERGs of 1–75 Hz and 75–200 Hz, respectively. The b–wave amplitudes were derived from the low band–pass filtered ERGs. The high–band–pass ERGs were further processed to rectify and integrate the waveform from 0–0.1 s after the flash. The maximum of the integral yielded the integrated OPs in microvolt * s. The values of both parameters at 0 and 15 min were compared statistically with repeated measures 2–tailed t–test with alpha = 0.05. Results: The mean b–wave amplitudes/standard error of the mean (sem) at 0 and 15 min were: 106/11 and 161/13 microvolts, p=0.01. The mean integrated OP amplitudes/sem were: 10/1.5 and 15/1.2 microvolt * s, p=0.01. The b–wave amplitude and the integrated OPs were both 1.5 times greater at 15 min than at 0 min of light adaptation. Conclusions: The equal and statistically significant increase in b–wave amplitude and integrated OP amplitudes indicate that both components contribute equally to the increase in the wide band–pass ERG during light adaptation. The data suggest that the cells of origin of both components are equally affected by the unknown process causing increase of the ERG arising in the cone system during light adaptation.
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