Breath taking                

A nerve neglected in today’s era of molecular and genetic analysis has yielded a surprising secret. A handful of neurons control breathing in a fine-tuned but powerful way, scientists have discovered in mice. Among these sensory neurons, two types are dedicated to two specific respiratory functions.

The findings, published in Cell, suggest new ways of considering clinical conditions related to the vagus nerve.

The team, led by Stephen Liberles, Harvard Medical School associate professor of cell biology, has effectively deconstructed the vagus nerve, a key connection between body and brain that is important because it controls not only breathing but also heart rate, feeding behavior and responses to illness.

Using genetic tools to activate these two neuron types with light, the scientists found that stimulating one neuron type caused mice to stop breathing completely, trapping them in a state of exhalation. Activating the second neuron type made the mice take rapid, shallow breaths, as if they had inhaled some kind of irritant to their lungs, hinting at a pulmonary defense mechanism.

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