2024-07-26 14:15:16
The indeterminate area in the center of the mammalian brain (uncertain zone) is involved in the integration of sensory information. Studies with mice show that as the pups develop her role is changing. In young pups, neurons in this area send information to other areas of the brain—such as the cerebral cortex—to initiate the growth of neurons in other areas.
Because the area’s role appears to be changing, Yuexuan Li of Yale School of Medicine and her colleagues wondered whether this part of the brain is involved in mother-infant bonding.
To investigate this, they first assessed which neurons in the area are activated when infants, still dependent on breastfeeding, interact with their mothers. For this, a fiber-optic probe was surgically implanted into the brain of some chicks. Using this probe, the researchers were able to detect the light emitted when neurons fire.
They found that the activated neurons express the hormone somatostatin, which regulates some body functions by inhibiting the release of other hormones (such as the stress hormone corticosterone).
Social interaction between mothers and pups activated these neurons, but contact with a toy did not.
The researchers were also interested in how this area of the brain might be affected by other social interactions. They found that contact with a lactating female who was not the cub’s mother, a non-lactating female, siblings, or an unrelated male also activated these neurons — but less than with the actual mother.
“Our results show that social interaction with the mother elicits the largest responses, about a 1.5-fold difference in average response levels compared to the other social stimuli studied,” says research team member Marcelo de Oliveira Dietrich, also at Yale.
In another part of the experiment, the team monitored brain activity when the chicks were socially isolated. During this time, which lasted from 10 minutes to 12 hours, the neurons were not activated, but this changed when they were given back to their mothers.
The encounter also reduced the babies’ stress response, as measured by whether they made “crying”-like sounds and the release of corticosterone.
Finally, the team wanted to see if artificially activating neurons while the chicks were isolated could reduce their stress. Using chemicals to activate neurons inhibited their “crying” and inhibited the release of corticosterone.
The researchers believe that the indeterminate area is probably involved in the development of early social relationships and other parts of the mammalian brain. They write that the “strong bond between young and mother” is “a hallmark of mammals.” The mother-child bond may involve the development of parts of the brain, with the indeterminate area acting as “the nexus where the features that define mammalian biology intertwine.”
Robert Froemke of NYU Langone Health, New York, says the study shows how certain neurons “primarily work to calm the baby down.” “However, it remains somewhat unclear how exactly the baby senses the mother (which aspects of smell, touch or perhaps temperature are important),” he says.
“Another open question is how much contact is required for security signals – how long do they last?” What promotes healthy development and what constitutes neglect?” For humans, “it’s likely that visual and acoustic cues—the sights and sounds of caregivers—would be just as important or perhaps more important than olfactory cues,” he says.
The study is published in the journal Science. Parengta pagal „New Scientist“.
2024-07-26 14:15:16