Is a retinal input involved in the generation of eye resetting fast phases in the frog eye optokinetic nystagmus?

An intravitreal injection of cis-2,3-piperidine dicarboxylic acid (PDA), a glutamate analog, in one eye only, decreased or even totally suppressed the eye resetting fast phases (ERFPs) of the frog optokinetic nystagmus (OKN) in monocular as in binocular situations. On the opposite, for low drum speeds, the slow phase eye velocity was not affected by PDA. Moreover, it seems that intravitreally injected PDA does not act upon central structures responsible for OKN. Our experiments suggest that a retinal input may be involved in triggering the ERFPs in the OKN.