Bright lights, not-so-big pupils

piggy submitted, created time 4 days 23 hours (www.eurekalert.org)

A team of Johns Hopkins neuroscientists has worked out how some newly discovered light sensors in the eye detect light and communicate with the brain. The report appears online this week in Nature.

These light sensors are a small number of nerve cells in the retina that contain melanopsin molecules. Unlike conventional light-sensing cells in the retina—rods and cones—melanopsin-containing cells are not used for seeing images; instead, they monitor light levels to adjust the body's clock and control constriction of the pupils in the eye, among other functions

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Removal of "superfluous" retina creates (time) blind mice...

Darkfrog submitted, created time 6 months 3 weeks (www.nature.com)

Removing a certain type of retinal cell from lab mice doesn't make them go blind, but it does shake up their body clocks; they quickly slip into a 23.5 hour cycle--the same as unaltered mice in total darkness. They also lost their ability to regulate pupil size, but not their other visual abilities, such as judging how far to jump to make it across a gap. This suggests that these melanopsin-expressing retinal ganglion cells (mRGCs) concern the detection of light, not the processing of visual information.

What I'm curious about now is whether blind humans do or do not have this problem

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