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Practice makes perfect: The human brain can reprogram itself to control prosthetic limbs
New research confirms that repeated use of an artificial limb leads the brain to rewire itself
By Florin Zubascu
The brain area that people use to recognise their own hands can be repurposed to operate an artificial limb, according to new research funded by the European Research Council. And the more a one-handed persons use the prosthesis in everyday life, the stronger their brain responds to it.
Researcher Tamar Makin of University College London and her colleagues hope that the new findings will help prosthetics manufacturers understand how to make more user-friendly devices. The findings could help improve rehabilitation strategies and prosthesis design and could also underpin future technologies to augment the human body.
“If we can convince a person’s brain that the artificial limb is the person’s real limb, we could make prostheses more comfortable and easier to use,” she says.
The research, published in medical journal Brain, is part of a growing body of fundamental science into how the brain senses and controls the world around it. In this case, the researchers scanned the brains of 32 subjects to assess their neural responses to images of prosthetic hands, including photos of their own prostheses, as well as real limbs. Half of the subjects were born with one hand and half had lost a hand due to amputation. Alongside them was a control group of 24 people with two hands.
The brain scans showed that the area that enables people to recognise hands was lighting up in response to images of prostheses among the one-handed participants who used a prosthesis most frequently in their daily lives, compared to the control group. This part of the brain also responded to images of prostheses that are functional but do not look like a hand, such as a hook prosthesis.
The researchers also looked at the neural connections between the separate brain areas that enable people to recognise hands and control them. The brain activity of the participants indicated that these two brain areas were better connected in people who used their prostheses regularly – an indication that the brain had rewired itself.
Loss of a hand, from birth or through accident, has a profound effect on how the brain organises itself. Exactly how is among the questions that Makin and others are trying to answer.
“We think the ultimate barrier is simply how much you use the prosthesis,” said Dr Makin.
The brain scans confirmed the impression of the study participants that, the more they used their prostheses, the more they felt like Participants in the study confirmed that their prostheses have an integral part of their bodies.
“I don’t regard it as an addition – I consider it a hand,” says study participant John Miller, who was born with only one hand and regularly uses his prosthesis.
“As many of our study participants lost their hand in adulthood, we find that our brains can adapt at any age, which goes against common theories that brain plasticity depends on development early in life,” says Fiona van den Heiligenberg of the UCL Institute of Cognitive Neuroscience, the study’s first author.
The study, funded by the European Research Council. was conducted by researchers at UCL and the University of Oxford, in collaboration with researchers from the Hebrew University of Jerusalem, the University of Western Ontario and Radboud University Nijmegen.