Horizontal optokinetic reflex in light reared and dark reared Israelian gerbils (Meriones tristrami).

Israelian gerbils (Meriones tristrami) reared in the dark from birth to 7-13 weeks of age show a clear optokinetic reflex in both horizontal directions under monocular viewing conditions. This is very different from gerbils reared in the light, which like many other mammals with lateral eyes show a clear monocular optokinetic reflex only in response to stimuli moving from temporal to nasal in the visual field. It is concluded that exposure to day light during the first postnatal weeks prevents the development of the naso-temporal component of the optokinetic reflex in the Israelian gerbil.