A squad of sensory cells in the throat prompts a reflex to keep the airways clear.

Sensory receptors in the gut and heart supply the brain with information, helping to control important functions such as food intake and heart rate. Now, researchers have pinpointed a group of sensory neurons in the throat that trigger protective responses when water or acid flows down the wrong pipe.

Working with mice, Stephen Liberles and his colleagues at Harvard Medical School in Boston, Massachusetts, used light to manipulate the function of sensory neurons in the larynx, which helps to carry air to the lungs. The researchers identified a handful of nerve cells that, when active, trigger responses that protect the airways, such as frequent swallowing, closure of the vocal cords, breath-holding and a cough-like reflex.

Each mouse had only 100 or so of these guardian neurons. Mice that lacked them showed almost no protective reaction when water or acid entered their windpipe.

Understanding how airway sensory neurons work could help scientists to develop better treatments for people with conditions such as chronic cough, the researchers say.