Human and macaque pupil responses driven by melanopsin-containing retinal ganglion cells

Vision Res. 2007 Mar;47(7):946-54. doi: 10.1016/j.visres.2006.12.015. Epub 2007 Feb 22.


Melanopsin, a novel photopigment, has recently been localized to a population of retinal ganglion cells that display inherent photosensitivity. During continuous light and following light offset, primates are known to exhibit sustained pupilloconstriction responses that resemble closely the photoresponses of intrinsically-photoreceptive ganglion cells. We report that, in the behaving macaque, following pharmacological blockade of conventional photoreceptor signals, significant pupillary responses persist during continuous light and following light offset. These pupil responses display the unique spectral tuning, slow kinetics, and irradiance coding of the sustained, melanopsin-derived ganglion cell photoresponses. We extended our observations to humans by using the sustained pupil response following light offset to document the contribution of these novel ganglion cells to human pupillary responses. Our results indicate that the intrinsic photoresponses of intrinsically-photoreceptive retinal ganglion cells play an important role in the pupillary light reflex and are primarily responsible for the sustained pupilloconstriction that occurs following light offset.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Electroretinography / methods
  • Humans
  • Light
  • Light Signal Transduction / physiology
  • Macaca mulatta
  • Photoreceptor Cells, Vertebrate / drug effects
  • Photoreceptor Cells, Vertebrate / physiology
  • Reflex, Pupillary / physiology*
  • Retinal Cone Photoreceptor Cells / drug effects
  • Retinal Cone Photoreceptor Cells / physiology
  • Retinal Ganglion Cells / physiology*
  • Retinal Rod Photoreceptor Cells / drug effects
  • Retinal Rod Photoreceptor Cells / physiology
  • Rod Opsins / physiology*


  • Rod Opsins
  • melanopsin