A new scientific breakthrough has led researchers to conclude that the feelings of itching and pain are relayed to the brain by different nerve cells. It was previously thought sensory nerve cells on the skin perceived both itching and pain. However, recent debate over this subject prompted a group of scientists at Johns Hopkins University to get to the bottom of it. In their experiments the scientists observed the reactions of mice to certain stimuli under different conditions. In the first experiment, the scientists isolated a type of nerve cell called MrgA3 by coating it with a glowing protein. They then exposed the mice to both pain and itch inducing stimuli, and found that MrgA3 sent a signal for both conditions. In another experiment, the researchers purposefully killed the MrgA3 cells so that they could observe how the mice responded to the same stimuli without them. They found that the mice acted in a similar way, albeit a stronger itching sensation was required to garner reactions similar in magnitude. This proved that there are other types of sensory nerve cells that are able to sense and relay the feeling of itchiness. In a final experiment, the scientists made it so that the MrgA3 cells were the only ones able to respond to a specific type of painful stimuli. After exposing the mice to the specific type of pain and to an itchy sensation, they found that in both cases the mice itched in response. This proved that MrgA3 nerve cells interpret both itchiness and pain as itchiness. This could potentially be very important to people who develop a chronic itch due to certain medications, or people with a phantom itch. Now that scientists know that only certain sensory nerve cells send the signal of itchiness to the brain, they may be able to shut them down when a patient has developed a chronic or phantom itch. Perhaps they will even come up with a way to stop the itch caused by wool sweaters, so during the next holiday season you won’t constantly be scratching when your mom forces you to wear one.