Newborn rats can “learn” the fears their mothers have, and then will carry those same fears for the rest of their lives, according to a study published in the Proceedings of the National Academy of Sciences. Researchers from the University of Michigan Medical School and New York University used electric shocks to train female rats to fear the smell of peppermint. They then exposed them to peppermint smells without shocks shortly after they gave birth, and discovered that the baby rats could detect through odor their mothers’ distress. Even though previous studies have shown that newborn rats generally are not able to learn, these baby rats began to fear peppermint just like their mothers.
“During the early days of an infant rat’s life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories,” said lead researcher Jacek Debiec, a psychiatrist and neuroscientist, in a press release. “Our research demonstrates that infants can learn from maternal expression of fear, very early in life. Before they can even make their own experiences, they basically acquire their mothers’ experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish.”
Learning the Smell of Fear: Mothers Teach Babies Their Own Fears via Odor (Press Release, University of Michigan, Newswise, July 28, 2014)
Intergenerational transmission of emotional trauma through amygdala-dependent mother-to-infant transfer of specific fear (Debieca, Jacek and Sullivana, Regina Marie. Proceedings of the National Academy of Sciences. July 2014. doi: 10.1073/pnas.1316740111)