Brain Activity Related to Missing Limbs

A study at Oxford University recently revealed that people born without one hand, who use both upper limbs in their daily routines, are likely to exhibit brain activity similar to that of able-bodied people.

The study at Oxford University, led by Dr Tamar Makin of the University’s Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), involved 14 participants born without one arm and 24 born with two arms. MRI scans were analysed to compare the activity of two corresponding areas in both sides of the brain. It was found that the activity of the disabled volunteers was overall asymmetrical due to disparities in the brain areas related to the missing and the unharmed hand.

A few people without one arm, however, had symmetrical activity patterns – nearly identical to the patterns of healthy participants. This discovery indicated that the more the stump or the prosthetic arm is used, the more the brain activity resembles that of an individual with two hands.

Previous studies have shown that unlike people born without one arm, people who lose their hand later in life often prefer to use their other arm to compensate for the missing limb. Gradually the brain area responsible for the movement of the amputated hand loses its original purpose. It is instead dedicated to the control over the intact hand.

The study might suggest ways to refine physical therapy so that people can achieve almost full functionality of their amputated limbs. Dr David Henderson Slater, a study co-author who is also a consultant at the Nuffield Orthopaedic Centre in Oxford, commented: “It is encouraging to see that there is hope for improvement even after devastating injuries, and to understand better what is going on inside the brain to make these behavioural adaptations,” adding that this knowledge may be used in future treatments given to new amputees.