Electroretinographic changes in aged pigeons.
Photopic electroretinograms, either to full-field light flashes (FERGs) or to contrast-reversal of square-wave gratings (PERGs) have been recorded in pigeons aged 2 years old (n = 5) and 10 years old (n = 5). Mydriatic pupil diameter, ophthalmoscopic appearance of the retinal fundus and optic media, and refractive state were comparable in the two groups. V/log I functions of individual FERG components (a-wave, b-wave and oscillatory potentials) displayed significantly lower slopes in the old birds than in the young, which suggests a reduction in retinal gain. PERG amplitude also was significantly lower in the older birds over a wide range of spatial frequencies (0.2-8.8 c/deg). Estimated visual acuity based on the extrapolated high-frequency cut off was 18 c/deg in the younger birds and 7.8 c/deg in the older birds. These results are in agreement with psychophysical data and retinal age-related losses in visual acuity, photoreceptors and retinal ganglion cells. Since these findings are comparable to those reported for humans, the results suggest that pigeons may serve as a useful model for human visual aging.
Porciatti
V
V
Institute of Neurophysiology, CNR, Pisa, Italy.
Hodos
W
W
Signorini
G
G
Bramanti
F
F
D000375:Aging / Q000502:physiology*; D000818:Animals; D010856:Columbidae / Q000502:physiology*; D004596:Electroretinography; D005260:Female; D008027:Light; D008297:Male; D010364:Pattern Recognition, Visual; D011601:Psychophysics; D012160:Retina / Q000502:physiology*; D014792:Visual Acuity