Localized Response of the Toad's Retina to Microillumination and Intermittent Light

Abstract

Slow potentials to microillumination (250×250 μ) were recorded at the same time with KCl-filled microelectrodes from the surface of the receptor layer and the inner plexiform layer of an inverted retina preparation of a toad. The surface response (response R) consisted of a slow positive- negative deflection, while the deep one (response D) consisted of an initial sharp negative and a second slower negative deflection.
1. The response D was more localized than the response R.
2. Both responses showed phase shifts during intermittent stimulation. Critical fusion frequencies were almost identical for both sorts of responses.
3. They varied independently as the intensity of illumination and the adaptation level were altered.
4. 10% CO₂ abolished first the response R and then the response D.