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Nose Learns Danger's Subtle Scent

Fear may heighten people's sense of smell, changing the
way people respond to scent, a new study shows.

The findings may hold clues for new anxiety disorder treatments, according to the

For the study, 12 healthy young adults took smell tests while getting their
brains scanned using functional magnetic resonance imaging .

First, participants sniffed scents from two bottles. The scents were almost
identical, with one subtle chemical variation. Participants couldn't tell the
two scents apart.

But when they smelled one of the scents while getting an uncomfortable, but
bearable, electric shock to their leg, they quickly learned to distinguish that
scent from its virtual twin.

The brain scans showed different patterns in brain activity when the
"danger" scent wafted through the air than brain activity when the
"no danger" scent was used.

"It's evolutionary," researcher Wen Li, PhD, of Northwestern
University's Feinberg School of Medicine, says in a news release. "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."

Li's team suggests that a breakdown in the ability to distinguish between
important and unimportant cues "may underlie the emergence of anxiety
disorders characterized by exaggerated sensory sensitivity and

If so, that could lead to a new approach to anxiety disorder therapies, the
researchers note in Science.

By Miranda Hitti
Reviewed by Louise Chang
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