researchers have identified neurons in the brains of baby mice that enable them to build a unique, strong bond with their mother in the first days of life.

Stimulating these neurons in mouse puppies that had been separated by their mother, the calming effect of the presence of their mother was able to imitate and reduce behaviors associated with stress.

The results science published today 1 offer new information Mother-child binding in mammals and could help researchers better understand how the development of the brain influences behavior.

"We know very little about how the brains of infants understand their social world," says study mitachor Marcelo Dietrich, a neurobiologist at Yale University. "When I founded my laboratory ten years ago and wanted to research this kind of things, people said that it was illusory. It will fail. It is too difficult." Now we show that it is possible: you can do rigorous science and try to understand these mechanisms that are potentially very important for development and health ”.

“I consider these neurons as the 'I feel good with Mama’s neurons," says Catharine Dulac, a neurologist at Harvard University. "The properties they discovered offer a framework to think about people."

binding in the brain

Dietrich and his team examined caring mouse puppies that were between 16 and 18 days old. They used live imaging techniques to record the activity in the zona incerta (zi), a thin layer of gray substance below the thalamus, while the animals interacted with their mother.

The ZI processes visual, auditory and sensory information. During the early development, it forms connections to various brain regions, some of which are withdrawn after weaning. The researchers found that neurons in the ZI of mouse puppies that produce a hormone called Somatostatin were active when they interacted with their mother. Somatostatin is involved in the regulation of many other hormones and processes in the body.

To test whether the activity of these neurons was specific to mother-child interactions, the authors watched the brains of mouse puppies while spending time with other, unknown mice, including other infident females, non-seeding females and adult males. They also tested whether the neurons reacted to control objects - rubber ducks and furry, mouse -shaped cat toys. "We just bought hundreds of it on Amazon," says Dietrich.

The somatostatin neurons did not react to the toys, but were activated to a certain extent, while the mouse puppies interacted with other adults, siblings and other puppies in the same age. But the reaction was not as strong as with her mother, which indicates that these neurons have a crucial role in the development of the unique mother-child bond.

“As these neurons realize that this is the mother and not someone else, is very fascinating," says Dulac.

The researchers also found that the activation of these neurons reduced the stress reactions in 11 days old puppies that had been separated from their mother: these puppies cried less and had lower mirrors of the stress hormone corticosterone than puppies where the neurons were not activated. Isolated puppies with activated somatostatin neurons also learned to form positive connections with certain smells, similar to how they did when their mother was present.

shift of the circuits

Although the study provides indications that somatostatin neurons in the ZI are involved in binding and reducing stress in mouse babies, the authors point out that studies on adult animals have shown different results.

The activation of these neurons in adult mice increased the with fear 2 3 connected reactions. "This is really impressive," says Johannes Kohl, a neurologist at the Francis Crick Institute in London. "The broader question arises whether it is really the same cells between newborns or before weaning and adults, or whether they are the same cells and they simply change their circuit integration radically and thus their role."

The authors say that these neuronal circuit circuits could go through changes if the mice age to help them adapt to different pressures in the course of their lives. "The longitudinal persecution of these neurons about the development could be very exciting to understand how they then take on their adult role," says Kohl.