A role for melanopsin in alpha retinal ganglion cells and contrast detection.
Distinct subclasses of retinal ganglion cells (RGCs) mediate vision and nonimage-forming functions such as circadian photoentrainment. This distinction stems from studies that ablated melanopsin-expressing intrinsically photosensitive RGCs (ipRGCs) and showed deficits in nonimage-forming behaviors, but not image vision. However, we show that the ON alpha RGC, a conventional RGC type, is intrinsically photosensitive in mammals. In addition to their classical response to fast changes in contrast through rod/cone signaling, melanopsin expression allows ON alpha RGCs to signal prior light exposure and environmental luminance over long periods of time. Consistent with the high contrast sensitivity of ON alpha RGCs, mice lacking either melanopsin or ON alpha RGCs have behavioral deficits in contrast sensitivity. These findings indicate a surprising role for melanopsin and ipRGCs in vision.
Johns Hopkins University, Department of Biology, Baltimore, MD 21218, USA. Electronic address: tmschmidt@jhu.edu.
Tiffany M
TM
Schmidt
Department of Physiology and Biophysics, Weill Cornell Medical College, Burke Medical Research Institute, White Plains, NY 10605, USA.
Nazia M
NM
Alam
National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Shan
S
Chen
University of Minnesota, Department of Neuroscience, Minneapolis, MN 55455, USA.
Paulo
P
Kofuji
National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Wei
W
Li
Department of Physiology and Biophysics, Weill Cornell Medical College, Burke Medical Research Institute, White Plains, NY 10605, USA.
Glen T
GT
Prusky
Johns Hopkins University, Department of Biology, Baltimore, MD 21218, USA; Johns Hopkins University, Department of Neuroscience, Baltimore, MD 21218, USA.
Samer
S
Hattar
D000200:Action Potentials / Q000187:drug effects / Q000235:genetics; D000818:Animals; D015350:Contrast Sensitivity / Q000235:genetics / Q000502:physiology*; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010852:Picrotoxin / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects / Q000235:genetics; D012160:Retina / Q000166:cytology; D012165:Retinal Ganglion Cells / Q000145:classification* / Q000502:physiology* / Q000648:ultrastructure; D017299:Rod Opsins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D013331:Strychnine / Q000494:pharmacology; D000099210:Melanopsin
D018683:Excitatory Amino Acid Agents; D018756:GABA Antagonists; D018684:Glycine Agents; D008164:Luminescent Proteins; D010852:Picrotoxin; D017299:Rod Opsins; D013331:Strychnine; D000099210:Melanopsin