Vision centres of blind person’s brain recycled to help other senses

By Thandi Fletcher, Vancouver Sun April 28, 2010, p. B 3

Despite popular belief, blind people don’t have a better sense of smell than people with sight, a 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 simply are 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 solely 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 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.

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