ScienceDaily (Mar. 31, 2008) — Each human nose encounters hundreds of thousands of scents in its daily travels perched front and center on our face. Some of these smells are nearly identical, so how do we learn to tell the critical ones apart?

Something bad has to happen. Then the nose becomes a very quick learner.

New research from Northwestern University's Feinberg School of Medicine shows a single negative experience linked to an odor rapidly teaches us to identify that odor and discriminate it from similar ones.

"It's evolutionary," said Wen Li, lead author of the study and a postdoctoral fellow at the Cognitive Neurology and Alzheimer's Disease Center at the Feinberg School. "This helps us to have a very sensitive ability to detect something that is important to our survival from an ocean of environmental information. It warns us that it's dangerous and we have to pay attention to it."

In the study, subjects were exposed to a pair of grassy smells which were nearly identical in their chemical makeup and perceptually indistinguishable. The subjects received an electrical shock when they were exposed to one scent, but not when they were exposed to the other similar one.

After being shocked, the subjects learned to discriminate between the two similar smells. This illustrates the tremendous power of the human sense of smell to learn from emotional experience. Odors that once were impossible to tell apart became easy to identify when followed by an aversive event.

Li and her colleagues also found specific changes in how odor information is stored in "primitive" olfactory regions of the brain, enhancing perceptual sensitivity for smells that have a high biological relevance.

The study will be published March 28 in the journal Science.

enlarge

Each human nose encounters hundreds of thousands of scents in its daily travels perched front and center on our face. Some of these smells are nearly identical, so how do we learn to tell the critical ones apart? Something bad has to happen. Then the nose becomes a very quick learner. (Credit: iStockphoto/Stacey Newman)

Related Stories

The Nose Knows: How Your Brain Helps You Become A Wine Expert (Dec. 24, 2006) — You don't need to sign up for pricey wine appreciation classes to parse the subtle difference between the bouquet of a pinot noir and a cabernet. Just pour yourself a couple glasses and sniff. Your ...  > read more

Who Moved My Cheese!? Researchers Find That 'One Sniff Will Do' For Odor Discrimination (Oct. 22, 2003) — By measuring the speed of smell, researchers at Cold Spring Harbor Laboratory have now found that unlike humans, rats can tell two very similar odors apart with just one sniff. And because it's ...  > read more

Sniff And Smell Are Equally Important In The Brain's Perception Of Odor (Oct. 21, 2003) — Imagine the smell of coffee in the morning. Did you close your eyes and inhale deeply through your nose? Neuroscientists at the University of California, Berkeley, found that most people do and that ...  > read more

Researchers Show How Brain Decodes Complex Smells (Jun. 18, 2006) — Duke University Medical Center researchers have discovered how the brain creates a scent symphony from signals sent by the nose. In studies in mice, the researchers found that nerve cells in the ...  > read more

Search ScienceDaily

Why I Hate Anchovies