July 6, 2005 -- Babies learn their mother's smell early in life, wiring the scent into their brains, new research shows.
That idea was tested on baby rats, not human infants. But the basic process may be similar, say the researchers.
Smell is one way that newborn animals (including humans) forge strong ties to their mothers, say researchers Kevin Franks, PhD, and Jeffry Isaacson, PhD.
Franks and Isaacson work in the neurosciences department of the medical school of the University of California, San Diego (UCSD). Their findings appear in Neuron.
Smell often brings memories back to life.
"Get a whiff of chocolate chip cookies baking in the oven, and the smell may conjure sudden fond memories of grandma's kitchen," says Benjamin Philpot, PhD.
He didn't work on the study, but he wrote an editorial in Neuron about it.
"Such strong odor associations are common, but we often take them for granted," says Philpot.
"However, for a newborn infant trying to locate mother's nipple, the association between odor and experience becomes a powerful force forming the basis of a strong bond between infant and mother," he says.
The baby rats in the UCSD test were around their mothers a lot for feeding and care. Each time, their tiny nostrils took in their mothers' scent.
The odor apparently became so familiar that the rats' brain cells started to recognize it quickly. In essence, the scent became wired into their brains through repeated exposure.
When one nostril was blocked, the lopsided odor exposure was reflected in the rats' brain development. The brain receptors that pick up odor on the side of the blocked nostril were developmentally delayed.
There may be a key time frame early in life when the development of nerve pathways takes place, say the researchers.
The same pattern has been seen as babies' visual systems develop, they say.
A Dad's Perspective
Philpot wore two hats, so to speak, when he wrote his editorial.
He's an assistant professor of cell and molecular physiology at the University of North Carolina at Chapel Hill. He's also a new dad.
Other simple but important factors could explain the observed brain changes, says Philpot.
But "as a neuroscientist and a new parent, I cannot help but to wonder whether a synaptic trace is being left in my newborn daughter's olfactory cortex every time she breastfeeds," he says.
In other words, his baby girl may be engraving her mother's scent in her mind, making it one of her life's earliest discoveries.