The earliest social memories of mice can be formed three days after birth

For mice, the earliest social memories can form three days after birth and continue into adulthood, the scientists report in the January 27 issue of Cell Reports, a journal of Cell Press Cell Press.
found that young mice preferred their mothers to strange females when they were born, and remembered their mothers 100 days later - although they preferred strange female mice as adults.
"I'm very interested in studying the development of social memory.
, "Social memory is our memory of others, including certain facts and characteristics about others," said lead author Blake J. Laham of Princeton University.
early memories can form long-term social connections and lay the foundation for future social interactions.
to understand how and when social memory began to develop, Laham studied the memories of mice to their mothers.
three-day-old mice's eyes and ears were not yet open, their bodies were pink, hairless, and half-transparent, and they could see the white milk in their stomachs.
that although mouse cubs of this age have poor motor skills, they can identify caregivers through their sense of smell.
because animals may be able to identify their biological mother solely on genetic basis, Larham and colleagues placed the young mice in "foster care" and were born under the care of a "nanny mother."
when Laham placed the mice between the mother mice who cared for them and the other unferented female mice, the mice kept swinging their tiny bodies and rotating them toward the mother mice that fed them.
also spend more time pointing their noses at the mother mice that care for them, a sign of recognition and preference.
authors found that these memories of adoptive mothers continued into adulthood, and that mice were able to recognize their mothers even after more than 100 days apart.
, "Once weaned, it's really interesting to see how this behavior changes."
" Laham said, "when animals no longer rely on their mothers to care for them, they are more likely to come into contact with new female mice."
"Laham believes that adult mice may be more interested in investigating whether strange mice are a threat or a potential mate.
to determine what these memories of mothers look like in the brains of mice, the researchers examined the areas of their body associated with social memory, CA2.
found that the young mice showed more biomarkers associated with neuron activity in the brain region after contact with the mothers who cared for them.
, adult mice also showed more of these markers after exposure to new mothers, suggesting that CA2 played a role in the behavioral transition.
also found that temporarily shutting down neuron activity in the CA2 region of young and adult mice impaired their ability to distinguish between caregivers and new mothers.
next step for Laham and his colleagues is to study how adjacent brain regions affect the phenomenon.
" our lives are made up of memories - but at the end of the day, all the memories that mean so much to us, inspire us, fill us with joy or fear, are just neurons communicating with each other.
it fascinates me.
," Laham said.
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