VEP and PERG acuity in anesthetized young adult rhesus monkeys

This study used the swept spatial-frequency method to compare retinal and c ortical acuity in anesthetized young: adult rhesus monkeys. Visual evoked p otentials (VEPs) and pattern electroretinographic responses (PERGs) were re corded from 25 monkeys (age range: 4-12 years) anesthetized with a continuo us infusion of propofol. The stimuli were temporally countermodulated sine- wave gratings that increased in spatial frequency within a 10.24-s period. All animals were refracted using acuity estimated from the zero micro-volt intercept of the linear regression of evoked potential amplitude on spatial frequency. Average sweep acuities were 23.7 cycles/deg +/- 1.5 S.E.M. and 23.1 cycles/deg +/- 1.8 S.E.M. for the PERG and VEP, respectively. VEP and PERG acuities were within the range expected based on acuities estimated fr om behavioral studies in macaques. PERG and VEP acuities were highly correl ated (r = 0.90) and equally sensitive to spherical blur. On a subset of ani mals, test-retest reliability of animals, and interocular correlations, wer e high (r = 0.87 and r = 0.83, respectively). Increasing propofol dosage 8- fold did not degrade PERG or VEP acuity. This study demonstrates that high spatial-frequency acuities can be rapidly obtained from young adult rhesus monkeys under a wide dose range of propofol anesthesia using the swept spat ial-frequency method.