Mother-child neurons

In humans, as in other mammals, infants have an innate tendency to form an attachment bond with their mothers or caregivers, a bond that plays a crucial role in the infant’s development. This bond helps newborns feel secure and serves as a safety net from which to explore their environment, learn, and develop crucial skills and behaviors. However, the neural mechanisms underlying these important social bonds during an infant’s development are not fully understood.

Since an infant’s response to its mother requires the integration of diverse streams of sensory input, the zona incerta (ZI), a brain region that serves as a hub for both external and internal stimuli, may play an important role in this process. Furthermore, previous research has shown that the zona incerta connects more densely to other brain regions early in life, but retracts these connections after weaning.

In a new study in preweaned mice, Yuexuan Li of Yale University in the United States and colleagues investigated the role that neurons in the zonulum play in integrating an infant’s early social experiences and facilitating maternal bonding.

Using fiber photometry, Li and colleagues recorded the activity of uncertain zone neurons in 16- to 18-day-old pups during interaction with their mother.

They found that the presence of the pup’s mother increased the activity of somatostatin-expressing neurons in the uncertain zone (ZISST neurons).

Artistic recreation of neurons. (Illustration: Amazings / NCYT)

Increased periods of social isolation between interactions with the mother did not change the activation response, suggesting that ZISST neurons track the presence and direct interaction with the mother.

Other forms of social interactions, including those with unfamiliar adults, peers, or siblings, also activated ZISST neurons, but much more modestly.

Furthermore, ZISST neurons integrate sensory signals, such as olfactory and whisker inputs, to respond to social interactions.

Removing both sensory inputs reduced activation, highlighting the importance of multisensory integration.

What was observed in the new study with mouse pups differs markedly from the effects of ZISST neurons in adult mice, where activation of the same neurons increases anxiety and fear responses, indicating that this neural circuit can adapt to support the distinct needs of individuals throughout development.

The study is titled “Neurons for infant social behaviors in the mouse zona incerta.” It was published in the academic journal Science. (Source: AAAS)