Roll the corner of a tissue into a fine point and drag it lightly across the fine hairs around your lips. Not the coarse, dark ones. The pale, short, barely visible fuzz. If you catch one at the right angle, you will want to scratch.
The psychologist Edward Titchener described this sensation in healthy volunteers in 1909, and the field largely left it alone for a century. A team at the University of Michigan has now identified the specific hairs and the specific nerve cells responsible, and in doing so has handed itch researchers something they have been short of: a target for the kind of itch that current medications do almost nothing for.
