If your mom is afraid of spiders, then there's a good chance you are too. We already know from previous research that parents' fears are transmitted to their children in different ways. This happens through genes, but also through the behavior parents show to their children. A study with rats has shown that smell also plays a role in this. Babies can smell by the scent of their fearful mother whether their mother is afraid. As a result, fear is transmitted from mother to child at a very early stage of development.

A previous study has already demonstrated the relationship between maternal odor and fear in infants. In this, rats were taught to be afraid of the smell of peppermint by having them smell this odor while giving them mild electric shocks. All this was done before the rats were pregnant. After the little rats were born, the researchers again made the mothers smell the peppermint scent without the shocks to trigger the fear response. The mothers gave off an odor that taught the babies to fear the smell of peppermint. The study also used a control condition of rats that had not been frightened by the peppermint scent.

In a follow-up study, the American scientists discovered a specific brain region that plays a role in this transmission of fear at a very young age. The researchers focused on lateral amygdala, an area involved in fear learning. The scientists gave some rats a substance that blocked activity in the amygdala. These rats did not learn to fear the peppermint smell. So, this shows that the amygdala is involved in this transmission.

What makes this finding so interesting is that babies at such a young age cannot learn based on their own experiences, but apparently can learn based on their mother's experiences. These results offer a new perspective on how mothers can transfer their fears to their children. This may help to devise new therapeutic treatments. The only question now is, does smell also play a role in this process in humans? Or is this way of transferring fear only possible in rats?

This article is a previously published brainmatters article written by Lorraine Fliek (14-8-14)

Reference:

Debiec, J., & Sullivan, R. M. (2014). Intergenerational transmission of emotional trauma through amygdala-dependent mother-to-infant transfer of specific fear. Proceedings of the National Academy of Sciences of the United States of America, 111(33), 12222–12227. https://doi.org/10.1073/pnas.1316740111