Rods in daylight act as relay cells for cone-driven horizontal cell-mediated surround inhibition

Nat Neurosci. 2014 Dec;17(12):1728-35. doi: 10.1038/nn.3852. Epub 2014 Oct 26.

Abstract

Vertebrate vision relies on two types of photoreceptors, rods and cones, which signal increments in light intensity with graded hyperpolarizations. Rods operate in the lower range of light intensities while cones operate at brighter intensities. The receptive fields of both photoreceptors exhibit antagonistic center-surround organization. Here we show that at bright light levels, mouse rods act as relay cells for cone-driven horizontal cell-mediated surround inhibition. In response to large, bright stimuli that activate their surrounds, rods depolarize. Rod depolarization increases with stimulus size, and its action spectrum matches that of cones. Rod responses at high light levels are abolished in mice with nonfunctional cones and when horizontal cells are reversibly inactivated. Rod depolarization is conveyed to the inner retina via postsynaptic circuit elements, namely the rod bipolar cells. Our results show that the retinal circuitry repurposes rods, when they are not directly sensing light, to relay cone-driven surround inhibition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nerve Net / physiology
  • Neural Inhibition / physiology*
  • Photic Stimulation / methods*
  • Retinal Cone Photoreceptor Cells / physiology*
  • Retinal Horizontal Cells / physiology*
  • Retinal Rod Photoreceptor Cells / physiology*