We define pain by its unpleasantness. Not so in the brain, where a sensation and its disagreeable quality seem to be independent. Scientists have long understood the signals nerves use to report pain to the brain. Now, researchers have discovered a set of neurons in a part of the mouse brain called the amygdala responsible for wrapping that signal in the garb of unpleasantness, NPR reports. The new study, published this week in Science, found that when these neurons were switched off, mice could still perceive what was previously painful, but they didn’t seem to care. The insights could inspire novel treatments to take the sting out of pain.