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Jan J Kremers, Avinash J Aher, Neil RA Parry, Nimesh Patel, Laura J Frishman; L- and M-cone driven ERG signals in macaques. Invest. Ophthalmol. Vis. Sci. 2020;61(7):762.
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© ARVO (1962-2015); The Authors (2016-present)
To study L- and M-cone driven ERGs of macaques for comparison with those obtained in human subjects.
ERGs were recorded from the right eyes of five anesthetized macaques (Macaca mulatta ; three males, two females). The 4-colour ganzfeld stimuli were luminance (22% contrast), L-cone excitation and M-cone excitation (both 22% cone contrast). Cone isolating stimuli were generated using triple silent substitution. The stimuli were sinusoidal (14 different temporal frequencies; 4 -56 Hz in 4 Hz steps), 4 Hz sawtooth and 2 Hz square wave temporal modulations.
The responses to sine-waves were dominated by the first (fundamental) component but there were more consistent second harmonic components than in humans. The first harmonic components showed multiple maxima and minima. The responses to low frequency luminance stimuli were smaller than those to cone isolating stimuli, where the average ERG L:M ratio was about unity and the L-M phase difference was 180°. At frequencies above 30 Hz, the luminance responses were larger than those to cone isolating stimuli. The averaged L/M ratio was about 2, with large inter-individual variability (between 1.5 and 16). The L- and M-cone driven responses had similar phases. The responses to sawtooth and square waves to luminance and cone isolating stimuli displayed substantially different On- and Off-responses. The L-On and M-Off responses resembled each other as did the L-Off and M-On.
The responses measured in macaques contained more substantial second harmonic components than those measured in human subjects, suggesting that macaque responses have stronger inner retinal origins (Hood et al., IOVS, 2002). Similar to the ERGs in humans, the responses reflect L-M cone opponency at low temporal frequencies and luminance activity above 30 Hz. Luminance signals display an average L:M ratio of 2 indicating that, similar as in humans, they are L-cone dominated. On- and Off-responses to cone isolating stimuli reflect mixed L/M cone opponent and luminance features in both macaques and humans.
This is a 2020 ARVO Annual Meeting abstract.
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