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Single-cell Suction Recordings from Mouse Cone Photoreceptors
Published on: January 5, 2010
Quantal noise from human red cone pigment
Yingbin Fu1, Vladimir Kefalov, Dong-Gen Luo
1Solomon H. Snyder Department of Neuroscience, Room 907 Preclinical Teaching Building, 725 North Wolfe Street, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Nature Neuroscience
|April 22, 2008
Summary
Quantal noise in human cone pigments was measured by expressing red cone pigment in mouse rods. This reveals a low dark rate, explaining comparable cone sensitivities across mammalian species.
Area of Science:
- Vision science
- Molecular biology
- Phototransduction
Background:
- Rhodopsin's spontaneous isomerization causes "dark light," setting rod vision thresholds.
- Quantal noise in human cone pigments is difficult to measure due to small single-photon responses.
Purpose of the Study:
- To measure the spontaneous isomerization rate of human red cone pigment.
- To understand the contribution of cone pigment noise to overall visual sensitivity.
Main Methods:
- Expressing human red cone pigment in genetically modified mouse rods.
- Utilizing the high sensitivity of mouse rods for detecting single-photon events.
- Measuring quantal noise in transgenic cone pigments after removing negative feedback.
Main Results:
- Quantal noise of human red cone pigment was measured in mouse rods.
- A dark rate of approximately 10 false events s(-1) cone(-1) was determined for native human red cones.
- This rate is significantly lower than previously reported primate cone dark transduction noise.
Conclusions:
- Mammalian red, green, and blue cones have comparable sensitivities due to low pigment noise.
- The study provides a molecular basis for similar cone sensitivities across species.
- This research clarifies a long-standing mystery in cone vision physiology.
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