Melanopsin-expressing ganglion cells in primate retina signal colour and irradiance and project to the LGN.
Human vision starts with the activation of rod photoreceptors in dim light and short (S)-, medium (M)-, and long (L)- wavelength-sensitive cone photoreceptors in daylight. Recently a parallel, non-rod, non-cone photoreceptive pathway, arising from a population of retinal ganglion cells, was discovered in nocturnal rodents. These ganglion cells express the putative photopigment melanopsin and by signalling gross changes in light intensity serve the subconscious, 'non-image-forming' functions of circadian photoentrainment and pupil constriction. Here we show an anatomically distinct population of 'giant', melanopsin-expressing ganglion cells in the primate retina that, in addition to being intrinsically photosensitive, are strongly activated by rods and cones, and display a rare, S-Off, (L + M)-On type of colour-opponent receptive field. The intrinsic, rod and (L + M) cone-derived light responses combine in these giant cells to signal irradiance over the full dynamic range of human vision. In accordance with cone-based colour opponency, the giant cells project to the lateral geniculate nucleus, the thalamic relay to primary visual cortex. Thus, in the diurnal trichromatic primate, 'non-image-forming' and conventional 'image-forming' retinal pathways are merged, and the melanopsin-based signal might contribute to conscious visual perception.
Dacey
Dennis M
DM
University of Washington, Dept of Biological Structure and the Washington National Primate Research Center, Seattle, Washington 98195-7420, USA. dmd@u.washington.edu
Liao
Hsi-Wen
HW
Peterson
Beth B
BB
Robinson
Farrel R
FR
Smith
Vivianne C
VC
Pokorny
Joel
J
Yau
King-Wai
KW
Gamlin
Paul D
PD
D000818:Animals; D002478:Cells, Cultured; D003118:Color Perception / Q000502:physiology*; D003624:Darkness; D006801:Humans; D066298:In Vitro Techniques; D008027:Light; D055537:Light Signal Transduction / Q000528:radiation effects; D008251:Macaca / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology / Q000528:radiation effects; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology / Q000528:radiation effects; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology / Q000528:radiation effects; D017299:Rod Opsins / Q000235:genetics / Q000378:metabolism*; D013787:Thalamic Nuclei / Q000502:physiology* / Q000528:radiation effects; D014795:Visual Pathways / Q000502:physiology / Q000528:radiation effects; D000099210:Melanopsin
D017299:Rod Opsins; D000099210:Melanopsin