A study of people born with one hand suggests neuroscientists may have fundamentally misunderstood the way the brain is organised, a scientist has claimed.
Dr Tamar Makin, of University College London, said the new theory – if proved correct – would have “massive implications”, adding it was “mind-blowing” to think that scientists could have been mistaken for so long.
An international team of researchers from the UK, Israel, Canada and Switzerland used an MRI scanner to monitor the brains of people who were born with one hand as they performed everyday tasks like handling money or wrapping a present.
They found the area of the brain associated with the missing hand was active when they used different body parts, such as the arm, foot and mouth.
Importantly this happened when these other body parts were used to perform the same function as the second hand in people with both, the researchers reported in the journal Current Biology.
This suggests that the brain is not organised so that each area is responsible for an individual body part, but that different areas are responsible for different functions.
Dr Makin said: “If true, this means we’ve been misinterpreting brain organisation based on body part, rather than based on function.
“It’s kind of mind blowing for me to think we could have been getting this wrong for so long.
“The implications, if this interpretation is correct, are massive.”
The study, she explained, suggested that it might be that “the hand area is not the hand area per se, but just the part of the brain in charge of function 'normally' carried by that hand”.
“In intact participants, all this is carried by the non-dominant hand,” Dr Makin said.
“But the fact that we see such a striking different representation in that area in congenital one-handers might suggest that this is not actually the hand area. “
She stressed the idea was still only a working theory.
If correct, it would be further evidence of the brain’s ‘plasticity’ – the idea that the brain is capable of reshaping itself and is not organised along rigid unchanging lines.
It is thought greater understand of the mechanisms involved could help find better ways for people with prosthetic limbs to control them using their mind.
“If we, as neuroscientists, could harness this process, we could provide a really powerful tool to better healthcare and society,” Dr Makin said.
“Unfortunately, this process is currently quite restricted in the brains of adults.
“But by learning how this occurs spontaneously in one-handers, we can get a handle on what we might be able to achieve.”