Circadian rhythms of rod-cone dominance in the Japanese quail retina.
When the Japanese quail is held in constant darkness, retinal responses (ERG b-waves) increase during the animal's subjective night and decrease during its subjective day. Rod photoreceptors dominate the b-wave responses (lambdamax = 506 nm) to all stimulus intensities at night but only to those intensities below the cone threshold during the day. Above the cone threshold, cones dominate b-wave responses (lambdamax, approximately 550-600 nm) during the day regardless of the state of retinal adaptation. Apparently a circadian oscillator enables cone signals to block rod signals during the day but not at night. The ERG b-wave reflects the activity of bipolar cells that are postsynaptic to rods and cones. The ERG a-wave reflects the activity of both rods and cones. The amplitude of the isolated a-wave (PIII) changes with time of day, as does that of the b-wave, but its spectral sensitivity does not. The PIII responses are maximal at approximately 520 nm both day and night and may reflect multiple receptor mechanisms. The shift in rod-cone dominance detected with the ERG b-wave resembles the Purkinje shift of human vision but, unlike the Purkinje shift, does not require a change in ambient light intensity. The shift occurs in constant darkness, with a period of approximately 24 hr indicative of a circadian rhythm in the functional organization of the retina.
Manglapus
M K
MK
Center for Vision Research, State University of New York Health Science Center, Syracuse, New York 13210, USA.
Uchiyama
H
H
Buelow
N F
NF
Barlow
R B
RB
D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D003118:Color Perception / Q000502:physiology; D003370:Coturnix / Q000502:physiology*; D008027:Light; D010775:Photic Stimulation / Q000379:methods; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*