Connexin hemichannel mediated ephaptic inhibition in the retina

► Horizontal cells feed back to cones via an ephaptic interaction. ► This interaction can occur due to three specializations. ► Open connexin hemichannels are located at the tips of horizontal cell dendrites. ► High extracellular resistance is presumably generated by proteoglycans. ► Low horizontal cell input resistance is due to inward rectifying potassium channels.