AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 5 637-R641, Copyright © 1983 by American Physiological Society
Canine visual acuity: retinal and cortical field potentials evoked by pattern stimulation
J. V. Odom, N. M. Bromberg and W. W. Dawson
The visual acuities (i.e., visual thresholds for pattern detection) of four
dogs under neuromuscular block were measured using visually evoked cortical
potentials (VECP) and/or pattern-evoked retinal potentials (PERR). Stimuli
were phase-reversing square-wave gratings with a mean luminance of 86 cd/m2
and 70% contrast. The mean of the VECP thresholds of two dogs tested was
12.59 cycles per degree (cycles/deg). The mean of the PERR thresholds of
four dogs tested was 11.61 cycles/deg. The difference between VECP and PERR
thresholds was not statistically significant. VECP acuities appear to be
determined at or before the last stage of retinal processing (PERR). Our
estimates of canine acuity are 1.3-2 times those reported for cats and
0.2-0.4 times those reported for primates when tested under comparable
luminance and contrast conditions.
