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With the help of a sophisticated tracing technique applied on mice, researchers discovered the neural circuitry that keeps us from biting our tongue. 

According to researchers, the study could offer insight into a variety of human behaviors from nighttime teeth grinding to smiling or complex vocalization. 

"Chewing is an activity that you can consciously control, but if you stop paying attention these interconnected neurons in the brain actually do it all for you," said Edward Stanek IV, lead study author and graduate student at Duke University School of Medicine, in the press release. "We were interested in understanding how this all works, and the first step was figuring out where these neurons reside."

Previous attempts of mapping the chewing control have produced a rather blurry picture. Up until now, researchers were aware of the various connections but were not exactly sure about which premotor neurons are connected to which motoneurons. 

In this study researchers used a special form of the rabies virus to trace the origins of chewing movements. Naturally, the rabies virus work by jumping backwards across neurons until it infects the entire brain of its victim.

"Using shared premotor neurons to control multiple muscles may be a general feature of the motor system," said Stanek. "For other studies on the rest of the brain, it is important to keep in mind that individual neurons can have effects in multiple downstream areas."

"This is just a small step in understanding the control of these orofacial movements," Stanek added. "We only looked at two muscles and there are at least 10 other muscles active during chewing, drinking, and speech. There is still a lot of work to look at these other muscles, and only then can we get a complete picture of how these all work as a unit to coordinate this behavior," said Stanek.

The study has been published in the journal eLife.