Diverse types of ganglion cell photoreceptors in the mammalian retina

Andrea Sand, Tiffany M. Schmidt, Paulo Kofuji*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

56 Scopus citations

Abstract

Photoreceptors carry out the first step in vision by capturing light and transducing it into electrical signals. Rod and cone photoreceptors efficiently translate photon capture into electrical signals by light activation of opsin-type photopigments. Until recently, the central dogma was that, for mammals, all phototransduction occurred in rods and cones. However, the recent discovery of a novel photoreceptor type in the inner retina has fundamentally challenged this view. These retinal ganglion cells are intrinsically photosensitive and mediate a broad range of physiological responses such as photoentrainment of the circadian clock, light regulation of sleep, pupillary light reflex, and light suppression of melatonin secretion. Intrinsically photosensitive retinal ganglion cells express melanopsin, a novel opsin-based signaling mechanism reminiscent of that found in invertebrate rhabdomeric photoreceptors. Melanopsin-expressing retinal ganglion cells convey environmental irradiance information directly to brain centers such as the hypothalamus, preoptic nucleus, and lateral geniculate nucleus. Initial studies suggested that these melanopsin-expressing photoreceptors were an anatomically and functionally homogeneous population. However, over the past decade or so, it has become apparent that these photoreceptors are distinguishable as individual subtypes on the basis of their morphology, molecular markers, functional properties, and efferent projections. These results have provided a novel classification scheme with five melanopsin photoreceptor subtypes in the mammalian retina, each presumably with differential input and output properties. In this review, we summarize the evidence for the structural and functional diversity of melanopsin photoreceptor subtypes and current controversies in the field.

Original languageEnglish (US)
Pages (from-to)287-302
Number of pages16
JournalProgress in Retinal and Eye Research
Volume31
Issue number4
DOIs
StatePublished - Jul 2012

Keywords

  • Circadian entrainment
  • Melanopsin
  • Photoreceptors
  • Pupillary light reflex
  • Retina
  • Vision

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Fingerprint Dive into the research topics of 'Diverse types of ganglion cell photoreceptors in the mammalian retina'. Together they form a unique fingerprint.

Cite this