Brain does not forget amputated limbs even after several decades

Human body is very adaptable to various changes that occur during your lifetime. You notice that when some functions of your body become impaired. For example, those who lose limbs learn o get around without them very quickly. Now scientists from UCL and the University of Oxford found that detailed information of a missing hand remains in brains over decades after amputation.

This is very interesting. Because human brain adapts to changing situation so quickly, you may think that data about the lost hand will be deleted almost instantly as it is not needed anymore. Building on previous work, when they used an ultra-high-power MRI scanner to look at the brain activity of two people who had lost their left hands, scientists hypothesized that information about lost limbs may be stored in the brain for decades. They used a brain-decoding technique based on the pattern of brain activity in 18 amputees.

All participants of this study lost their one of their hand each to amputation on average 18 years ago. Also, all of them experienced some sort of phantom sensations. Scientists also gathered a group of 13 people who were missing one hand from birth. Finally, there was also a third group used as a control. Scientists asked these people to move fingers on the missing hand (or one of the hands if none were missing). At the same time they performed MRI scans and compared the results of all three groups. Scientists found that people who had one of their hands amputated, displayed a neural fingerprint dedicated to their missing hand, even if they barely experienced any phantom sensations. Meanwhile people born with missing limbs showed some activity, but nothing even remotely similar in scale.

Scientists say that these findings could lead to development of the next-generation of neuroprosthetics. These highly advanced devices could essentially tap into the brain’s control centre, becoming almost a natural-feeling limb, which can be controlled effortlessly. Dr Tamar Makin, senior author of the study, said: “Our work suggests that daily life experience could shape the fine-grained aspects of hand representation, but that the large-scale functional organisation of the hand area is fundamentally stable”. Of course, this study also shows that creating neuroprostheses or performing hand transplants to people born without a hand would be very challenging.

Human brain is a very peculiar apparatus. It may adapt itself in funny ways, but it seems like it doesn’t repurpose the real estate dedicated to a limb once it is lost. Scientists are hoping to take advantage of this phenomenon by creating a new generation of prosthetics.

Source: UCL