The area of the brain used to control the hand gets used instead to support the lips, feet or arms of people who were born with only one hand, finds a new study led by researchers at UCL and the Weizmann Institute of Science in Israel.
For the study, published this week in Current Biology, 17 people who were born without one hand and 24 two-handed controls completed tasks such as opening a bottle, folding laundry or taking cash out of a wallet. Those with one hand had different strategies such as using their lips, legs, prosthesis or residual arm to do something most people would do with two hands. They were then asked to move those body parts while in an fMRI scanner. The scan showed that the “hand area” of the brain’s sensorimotor cortex was being employed by those body parts one-handers used instead of their hand.
Dr Makin said the findings could also challenge conventional wisdom in the field that the brain is mapped based on which body part each brain region controls.
The authors say they hope their findings could lead to more research into how to best integrate assistive and augmentative technology such as artificial arms, if researchers can gain more insight into the process of brain reorganisation.