Role of a novel photopigment, melanopsin, in behavioral adaptation to light

S. Kumar Nayak, T. Jegla, S. Panda

Research output: Contribution to journalReview articlepeer-review

39 Scopus citations


Adaptation to changes in the ambient light is of critical importance to life. In mammals, three principal photoadaptation mechanisms depend on ocular photoreception and exhibit spectral sensitivity suggestive of the opsin class of photopigment(s). These include rapid adaptation of the visual system to the ambient light by pupil constriction, direct modulation of neuroendocrine function and entrainment of the circadian clock to the day:night cycle. Surprisingly, these processes can largely function independent of classical rod/cone photoreceptors, suggesting a novel opsin-based signaling mechanism. They appear to involve a recently discovered network of intrinsically photosensitive retinal ganglion cells that make direct or indirect axonal connections to brain centers regulating photoadaptive behaviors. The discovery of a novel opsin, melanopsin, in these cells has offered an exciting entry point to explore, at the molecular level, how mammals adapt to their light environment. There is now genetic proof of a principal role for melanopsin in all three major photoadaptation processes.

Original languageEnglish (US)
Pages (from-to)144-154
Number of pages11
JournalCellular and Molecular Life Sciences
Issue number2
StatePublished - Jan 2007

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Molecular Biology
  • Pharmacology
  • Cellular and Molecular Neuroscience
  • Cell Biology


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