New study shows despite myth, blind people don't have a better sense of smell

From Canwest News Service:

Despite popular belief, blind people don't have a better sense of smell, a new Canadian study suggests.

University of Montreal graduate student Mathilde Beaulieu-Lefebvre debunked the myth that blind people have a more acute sense of smell, finding instead they are simply more conscious of odours around them.

"The urban legend is not true," Beaulieu-Lefebvre said.

It's not their sense of smell that's different, but rather the way blind people use their noses, she said. For example, while a sighted person can simply look at food and tell if it's gone bad, a blind person relies on smell to recognize good food from spoiled food.

"In the absence of vision, (blind people) have to rely on other cues, like smell or sound," Beaulieu-Lefebvre said.

However, the study did find that blind people process odour information in their brains differently from sighted people.

Using a type of MRI scan, the researchers discovered that when blind people smell something, they use the part of the brain connected to the nose more than other people. They also found that — despite having lost their sense of vision — blind people still use the occipital cortex, the part of the brain used for vision.

"This part of the brain is sort of recycled to do tasks other than vision, such as smelling or touching or hearing," explained Beaulieu-Lefebvre.

The researchers studied 25 participants, 11 of whom were blind from birth.

First, subjects were asked to identify and tell the difference between 16 different perfumes. Then, the researchers analyzed the subjects' brain activity while they smelled different odours: a rose, vanilla and butanol, a type of sweet-smelling alcohol.

As the study only looked at participants who were born blind, Beaulieu-Lefebvre said there could be different results for people who become blind later in life.

The study's findings can help researchers better understand how the human brain works, Beaulieu-Lefebvre said.

"This gives hope to blind people in understanding that the brain is not hardwired," she said. "It can be reorganized to do different tasks."

The research can also help to develop a rehabilitation program for the blind, where they can learn how to navigate through an environment based on smell, she said.

Mike Potvin, who lost his vision at 25 to a rare hereditary disorder called Leber's optic neuropathy, is not surprised by the study's findings.

"It's a common misconception that people often bring up with me, and I always tell them, close your eyes for 10 minutes and see if you can smell or hear any better," said Potvin, who works as the programs and communications manager with the Canadian Council of the Blind.

While Potvin does still have some peripheral vision, he said he does rely more on other senses, including hearing and smell, to give him "a sense of orientation."

For example, "if I come across the smell of bread baking, then I know I'm close to the grocery store that's close to my work," he said.

Beaulieu-Lefebvre will be presenting her findings in June at a conference for the Organization for Human Brain Mapping.