Lit. Cells expressing retinal melanopsin, like the one shown here, could explain why light is so painful for migraine sufferers.
R. Noseda et al., Nature Neroscience , Advance Online Publication (January 2010)
Migraine sufferers often withdraw into a room dark or pull the shades down. All the light is simply the worst burning pain. Now scientists think they know why -. With the help of blind volunteers
Just why light worsens migraine is uncertain, because the brain regions that govern vision do not overlap with those that transmit pain. To narrow vision which the cells could be behind this, anesthetist Rami Burstein, who works at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, and colleagues tracked migraine sufferers who also happened to be blind. Of the 20 blind people who volunteered for the study, six could not perceive light at all; they lacked eyes or had a severely damaged optic nerve, which connects the eye to the brain. The other 14, who suffered from genetic and other conditions that lead to blindness, could not see, but they could feel certain shades of light.
Not surprisingly, the six people who had no vision at all don 't experience the pain of light when they had a migraine. But the other 14 did. It was an interesting clue, because these people had failed rods and cones, the cells of the retina that are most light detection work. They did, however, have other retinal cells that worked very well, especially those with a type of receptor called melanopsin. Melanopsin does not allow people to see shapes, but it reacts to light -. Specifically, light blue
At this point, said Burstein, "we should follow melanopsin," to see if the cells expressing it could connect with the cells that transmit pain. And indeed, in rat brain, the axons of the cells sensitive melanopsin light clinging to specific nerve cells in the thalamus that play a role in pain sensation, reports online this week in team Nature Neuroscience .
"This kind of approach is exactly the kind of thinking we need" in medicine, says Kathleen Merikangas, genetic epidemiologist at the National Institute of mental health in Bethesda, Maryland. it welcomes the decision of an exceptional group of people strategy, and then plot the results back in an animal model. the work "really breaks significant new ground" by assembling why light is so painful during a migraine, agrees David Berson, a neuroscientist at Brown University who helped discover the melanopsin receptors several years ago. He cautions, however, that voluntary blind study might still have sticks cells and cones intact, meaning that melanopsin could be only a piece of the puzzle in light of the pain.
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