Related Experiment Video
Updated: Aug 8, 2026

Simultaneous Whole-cell Recordings from Photoreceptors and Second-order Neurons in an Amphibian Retinal Slice Preparation
Published on: June 1, 2013
Sustained feedback effects of L-horizontal cells on turtle cones
Abstract:
Prolonged stimulation of the periphery of their receptive field can evoke in turtle cones sustained complex depolarizations or sustained membrane oscillations. In cones in which such effects of prolonged peripheral stimulation are not apparent, the injection of short depolarizing pulses can reveal a sustained increase of electrical excitability in response to prolonged peripheral illumination. The sustained effects of prolonged peripheral illumination have characteristics similar to those of the feedback depolarizations evoked by flash peripheral stimulation: they are labile in untreated retinas, can be blocked by either hyperpolarization, Co2+ or agents that depolarize the L-horizontal cells. They are associated with a decrease in the membrane input resistance. In retinas bathed in Sr2+- or Ba2+-containing media, prolonged peripheral illumination evokes a sustained repetitive discharge of spikes. These experiments demonstrate that the feedback effects of the L-horizontal cells on the cones are not only transient but also sustained and that the sustained effects of peripheral stimulations are associated with an increase in membrane Ca2+ conductance. The possible nature of the feedback connection between L-horizontal cells and the cones is discussed.
More Related Videos
Related Concept Videos
The Retina
Vision
Unrenewable Cells
Photoreceptors
The retina is composed of several layers and contains specialized cells called photoreceptors. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. There are two types of photoreceptors—rods and cones—which differ in the shape of their outer...
Anatomy of the Eyeball
Photoreceptors and Visual Pathways
Color Vision

