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Y. Umino, E. Solessio, R. Hermann, V. Arshavsky, R. Barlow; Temporal Vision of R9AP Knockout Mice With Slow Photoreceptor Inactivation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3863. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Study the relationship between temporal visual sensitivity and photoreceptor inactivation kinetics.
We tested the visual sensitivity of wildtype (C57BL/6J) and R9AP-/- mice by measuring their threshold for optomotor responses to rotating sinusoidal gratings (Optomotry©) using a double-blind protocol. R9AP is an anchoring protein for GTPase activation that controls transducin-α inactivation. Its absence slows down photoreceptor inactivation without affecting the sensitivity and onset kinetics of rod and cone photoreceoptors. We measured temporal contrast sensitivity for of WT and KO mice over a range of spatial frequencies under both scotopic (-4.5 log cd/m2) and photopic (1.8 log cd/m2) conditions.
R9AP KO mice have lower sensitivity than WT mice for high temporal frequencies under photopic but not scotopic conditions. The loss of temporal contrast sensitivity by KO mice is greatest for high spatial frequencies. The decreases in spatiotemporal sensitivity of KO mice narrow the range of temporal vision. The temporal contrast sensitivity functions of KO mice together span the frequency range of 0.07 to 10 Hz, whereas those for WT mice cover the range of 0.04 to 20 Hz. The photopic functions of KO mice share properties with their own scotopic functions and those of WT mice suggesting that cone vision of R9AP-/- mice has acquired "rod-like" temporal properties. Under scotopic conditions WT and KO mice exhibit similar temporal contrast sensitivities indicating that slowed photoreceptor inactivation does not significantly impact rod-mediated vision.
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