Is the Wheelchair a Part of the Body? Your Brain May Think So

A new study suggests that a wheelchair can actually become a "part" of the user's body, replacing the limbs that no longer function in the wheelchair user's brain. It has long been known that the brain has a certain degree of "plasticity"--the ability to change function over time according to usage. "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, D.C.

When humans lose the use of a sensory organ, such as their eyes or ears, the portion of the brain controlling that input can be redistributed to the other senses, making them more acute. The study performed by Mariella Pazzaglia of Sapienza University of Rome, Italy, suggests that this form of plasticity also occurs in people who suffer from non-sensory disabilities, such as losing the use of their legs. Human beings, when using tools such as a toothbrush or a hammer, treat those tools as extensions of the body, but according to the study, the wheelchair is actually treated less like an extension of the body, and more like an actual part of it. "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," Pazzaglia said. "All daily activities become an automatic way of thinking, not merely a mechanical or practical process."

The study surveyed 55 people with spinal cord injuries who needed wheelchairs for mobility and asked questions about their lives. The analysis of their answers shows that the more a person can interact with their wheelchair, the stronger the mental connection becomes between the wheelchair and the person’s body. Thus, those who had more upper-body strength also had a better relationship with their wheelchair. This means that using the chair itself becomes less of a conscious effort, and more of an automatic response. That, in turn, 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." Not sure if "automatic thinking" or "brain plasticity" explain bungee jumping in your chair, however!

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