The brains of disabled people adjust to a wheelchair and treat it as an extension of their body, essentially replacing limbs that don't function properly anymore, new research suggests.
The findings provide more insight into how the brain compensates when it uses tools like a wheelchair, or even something as simple as a hammer or toothbrush, said study lead author Mariella Pazzaglia, an assistant professor at the Sapienza University of Rome, in Italy.
In the future, Pazzaglia said, this kind of research could lead to ways to enhance the body in people who are physically impaired. "Bodily representations can be extended to include exoskeletons, prostheses, robots and virtual avatars," she said.
At issue is what scientists call "brain plasticity," which describes the brain's ability to learn and adjust, something people do quite often when young and continue to do as they get older.
"If we learn how to play a piano or drive somewhere, that's plasticity in action," said Dr Alexander Dromerick, chief of rehabilitation medicine at Georgetown University Medical Center in Washington, DC.
The human and body
Human brains also can compensate for bodily changes such as the loss of a limb by adjusting what's known as the internal body map. The new study sought to understand how the brains of disabled people change their body maps to include wheelchairs.
The researchers surveyed 55 people in wheelchairs with spinal cord injuries about their lives, and then analyzed their responses. The study authors determined that the participants treated wheelchairs as part of their bodies, not simply as extensions of their limbs.
The study also found that people who had more movement in their upper limbs could interact more with wheelchairs, and this improved their ability to incorporate them into their body images.
Essentially, the participants' brains go into an automatic mode when it comes to using the wheelchairs. This leads to "more efficient and safer use, with lower costs, risks and dangers to the body," Pazzaglia said.
"To elude dangerous objects in the environment and the collisions that may occur during wheelchair use, the brain needs to encode an internal representation of the body that includes the wheelchair," she said.
People and their daily activities
"Moreover, the simple action of picking objects up from the floor without tipping out of the wheelchair implies a change in the representation of the body to enable this to happen successfully and without the risk of possible damage to the individual due to a fall," she added. "All daily activities become an automatic way of thinking, not merely a mechanical or practical process."
Automatic thinking - based on body maps that encompass inanimate objects - plays plenty of other roles in people's lives, Georgetown's Dromerick said. For example, people who can wield a hammer effectively or parallel park with ease have learned to treat hammers and cars as extensions of themselves, he said.
The study appeared in the journal PLoS One.
For more on disabilities, visit the U.S. National Library of Medicine.