Mice exposed to scents of mint or fresh-cut grass before and shortly after birth show increased responses in a specific population of odor-processing neurons to a variety of odors, according to new research published in eNeuro. The study demonstrates how early experience shapes the brain’s processing of the sense of smell.

Annie Liu, who is in Pitt's MD-PhD graduate training program, and neurobiologist Nathan Urban, PhD, fed food infused with two odorants to breeding pairs of mice.  One odorant (methyl salicylate, which smells like wintergreen) and the second (hexanal, which smells like cut grass) activate different but overlapping areas of the olfactory bulb. Following odorant exposure, the litters were weaned onto the same diet as their parents. During exposure to varying concentrations of eight different odors, mice exposed to one of the scented diets during gestation and early life had stronger responses of a greater number of mitral cells than mice exposed to an unscented control diet. Mitral cells are critical for relaying olfactory information from the olfactory nerve to other parts of the brain. The effect did not depend on the particular odor to which mice were exposed; mice fed either one of the scented diets displayed heightened mitral cell responses to all presented odors.