Researchers have discovered two tiny clusters of neurons in the brain stem in mice. These clusters were observed to regulate process of sigh in those rodents, which are believed to possess respiratory system similar to that in human. The new findings may help in understanding other factors leading to more complex behaviors in human.

The brain has a breathing center which regulates breathing rhythm as well as the kind of breath we take. The center has different kinds of small neurons. These neurons work as buttons to turn on different breath process, that are regular breath, sigh, yawn, sniffs, cough and many other.

A sigh is the product of 200 or so neurons in the brain stem in rodents. The sigh re-inflate errant alveoli, balloon-like structures, which when collapse can cause difficulty in breathing. There are around 500 million tiny alveoli in lungs. On average, a person sighs every five minutes or about 12 times an hour. Sigh is essential to preserve lung functions.

"Sighing appears to be regulated by the fewest number of neurons we have seen linked to a fundamental human behavior, Our finding gives us insights into mechanisms that may underlie much more complex behaviors", said Jack Feldman, a member of the UCLA Brain Research Institute.

When bombesin was injected into breathing center, the rate of sigh in mice increased significantly, leaving the breathing pattern intact. The researchers found two clusters of cells responding to bombesin, each cluster had about 200 brain cells that responded to different form of bombesin.

The research concluded that there may be similar cluster in human brain regulating in them. The findings could help in finding remedies to problems related to mental disorder and anxiety.