Yawn! Did That Make You Yawn?

       Why do so many of us yawn in response to others doing so? It is a phenomenon known as contagious yawning. Humans aren’t alone in this odd practice. Monkeys, chimpanzees, and even dogs will often yawn if they see—or even hear—someone else doing it.

    Studies suggest that contagious yawning isn’t wholly within our control. Some people are more susceptible to contagious yawning than others. To understand why this variability exists, researchers exposed patients to yawning videos. They attached each subject to a Transcranial Magnetic Stimulation (TMS) device, a machine that uses magnetic waves to measure what’s known as motor cortical excitability. Motor cortical excitability is a measure of how easily neurons fire or how "excitable" brains are. It turns out that people with more excitable motor cortexes tend to yawn more frequently. It makes sense that having a more impulsive brain would make something instinctive and involuntary happen more easily. 

    Evidence suggests that the same part of the brain responsible for our involuntary yawning is also involved in some nervous system disorders like Tourette’s syndrome.  In the long run, gaining better insight into why we yawn—and how these electrical signals give rise to involuntary behaviors—might help us develop new treatments to tackle disorders like Tourette’s, Attention Deficit and Hyperactivity Disorder, and perhaps even schizophrenia.