Sunday 22 December 2013

No Blue Skies for Mice: Scientist Study Differential Distribution of Photoreceptors in Retina of Mice

Dec. 4, 2013 — Guppies, hyenas and mice share one particular retinal specialization in their eye: Photoreceptors ("cones") sensitive to 'green' light are largely located in the top half of the eye, whereas cones sensitive to 'blue' light dominate the bottom half. Since the lens inverts the image as it enters the eye this arrangement seems to make intuitive sense: blue light from the sky is detected by the blue cones, while the greenish light from the ground falls onto the green cones.

Scientists led by Thomas Euler at the Werner Reichardt Centre for Integrative Neuroscience at the University of Tübingen have investigated this retinal specialization in mice. In their study, just published in the journal Neuron, they show that this arrangement is not an adaptation to the predominating 'colors' of the sky and the ground, as was previously thought. Their experiments showed that the apparent match between 'color' and differential cone distribution brings the animals no advantage. "The green cones would 'see' the light in the sky just like the blue cones," explains Thomas Euler. Instead, this specialized distribution of cones appears to subserve a much more fundamental aspect of vision: the detection of dark-light contrasts.

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