How mammals' brains evolved to distinguish odors is nothing to sniff at

JULY 18, 2019

by Salk Institute

The world is filled with millions upon millions of distinct smells, but how mammals' brains evolved to tell them apart is something of a mystery.

Now, two neuroscientists from the Salk Institute and UC San Diego have discovered that at least six types of mammals—from mice to cats—distinguish odors in roughly the same way, using circuitry in the brain that's evolutionarily preserved across species.

"The study yields insights into organizational principles underpinning brain circuitry for olfaction in mammals that may be applied to other parts of the brain and other species," says Charles Stevens, distinguished professor emeritus in Salk's Neurobiology Laboratory and coauthor of the research published in the July 18, 2019 issue of Current Biology.

In brief, the study reveals that the size of each of the three components of the neural network for olfaction scales about the same for each species, starting with receptors in the nose that transmit signals to a cluster of neurons in the front of the brain called the olfactory bulb which, in turn, relays the signals to a "higher functioning" region for odor identification called the piriform cortex.

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