Kinetics of Inhibitory Feedback from Horizontal Cells to Photoreceptors: Implications for an Ephaptic Mechanism.

ABSTRACT:

Unlabelled

Inhibitory feedback from horizontal cells (HCs) to cones generates center-surround receptive fields and color opponency in the retina. Mechanisms of HC feedback remain unsettled, but one hypothesis proposes that an ephaptic mechanism may alter the extracellular electrical field surrounding photoreceptor synaptic terminals, thereby altering Ca(2+) channel activity and photoreceptor output. An ephaptic voltage change produced by current flowing through open channels in the HC membrane should occur with no delay. To test for this mechanism, we measured kinetics of inhibitory feedback currents in Ambystoma tigrinum cones and rods evoked by hyperpolarizing steps applied to synaptically coupled HCs. Hyperpolarizing HCs stimulated inward feedback currents in cones that averaged

SUBMITTER: Warren TJ 

PROVIDER: S-EPMC5039255 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature