title: Dark light, rod saturation, and the absolute and incremental sensitivity of mouse cone vision.
abstract: Visual thresholds of mice for the detection of small, brief targets were measured with a novel behavioral methodology in the dark and in the presence of adapting lights spanning ∼8 log(10) units of intensity. To help dissect the contributions of rod and cone pathways, both wild-type mice and mice lacking rod (Gnat1(-/-)) or cone (Gnat2(cpfl3)) function were studied. Overall, the visual sensitivity of mice was found to be remarkably similar to that of the human peripheral retina. Rod absolute threshold corresponded to 12-15 isomerized pigment molecules (R*) in image fields of 800 to 3000 rods. Rod "dark light" (intrinsic retinal noise in darkness) corresponded to that estimated previously from single-cell recordings, 0.012 R* s(-1) rod(-1), indicating that spontaneous thermal isomerizations are responsible. Psychophysical rod saturation was measured for the first time in a nonhuman species and found to be very similar to that of the human rod monochromat. Cone threshold corresponded to ∼5 R* cone(-1) in an image field of 280 cones. Cone dark light was equivalent to ∼5000 R* s(-1) cone(-1), consistent with primate single-cell data but 100-fold higher than predicted by recent measurements of the rate of thermal isomerization of mouse cone opsins, indicating that nonopsin sources of noise determine cone threshold. The new, fully automated behavioral method is based on the ability of mice to learn to interrupt spontaneous wheel running on the presentation of a visual cue and provides an efficient and highly reliable means of examining visual function in naturally behaving normal and mutant mice.
authors.affiliation: Department of Psychology, Northeastern University, Boston, Massachusetts 02115, USA. f.naarendorp@neu.edu
authors.forename: Frank
authors.initials: F
authors.lastname: Naarendorp
authors.forename: Tricia M
authors.initials: TM
authors.lastname: Esdaille
authors.forename: Serenity M
authors.initials: SM
authors.lastname: Banden
authors.forename: John
authors.initials: J
authors.lastname: Andrews-Labenski
authors.forename: Owen P
authors.initials: OP
authors.lastname: Gross
authors.forename: Edward N
authors.initials: EN
authors.lastname: Pugh
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000528:radiation effects; D002138:Calibration; D003624:Darkness; D005260:Female; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000528:radiation effects; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000528:radiation effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology* / Q000528:radiation effects; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology* / Q000528:radiation effects; D015293:Transducin / Q000235:genetics / Q000528:radiation effects; D014785:Vision, Ocular / Q000502:physiology* / Q000528:radiation effects
chemical_list: D044385:GTP-Binding Protein alpha Subunits; C488949:Gnat1 protein, mouse; C515337:Gnat2 protein, mouse; D020962:Heterotrimeric GTP-Binding Proteins; D015293:Transducin