Many people, even very far from transplantation, have heard of such a concept as phantom pain. These sensations arise in hospital patients after amputation: it seems to a person that he feels pain in a limb, which in fact he has not had for a long time.
In addition, after amputation, many patients experience their phantom limb, sometimes for several years. The nature of the phenomenon is still poorly understood, but new research may help in this matter.
A team of scientists from Oxford University examined the brain activity of amputated patients using a high-power CT scanner. The first participant in the experiment lost his arm 25 years ago, the second - 31 years ago. Both had a pronounced phantom syndrome all this time.
In parallel, neuroscientists studied data from a control group - 11 people who had both hands, and all subjects were left-handed. During the experiment, participants had to move each finger of their left hand separately.
Scientists have found that even after amputation of a limb, the brain structures responsible for controlling them still perfectly “remember” the lost hands.
“We found that in people with amputated arms, the brain activity associated with the left arm was reduced. At the same time, certain patterns corresponding to the image of the hand coincided with the patterns of people from the control group,”says lead author Tamar Makin.
This can be clearly seen in the presented diagram. Black arrows indicate the correspondence of the fingers to the areas of the brain marked with colors: thumb - red; index - yellow; medium - green; the nameless is blue, the little finger is purple. The first diagram reflects the work of the brain of the participants in the control group, the second - of people after the amputation of the arm (above and below the elbow). FDR is the false detection rate and “q” is the level of error.
Promotional video:
It turns out that even after removing individual fingers, people still have the ability to send a signal for their movement, squeezing, straightening and other functions.
Until now, most neuroscientists were convinced that the process of hand control takes place in the somatosensory cortex of the brain and can only be maintained in the presence of systematic feedback from nerve endings. It turns out that this is not so: if the "rewriting" of the nervous map occurred in the absence of feedback signals, then people who lost their hands would not have phantom pains.
Having studied the brain activity of amputees using computed tomography, scientists have come to the conclusion that the brain still "remembers" lost hands well. The new discovery could be a big breakthrough in the field of prosthetics and will allow in the future to create prostheses that can be controlled directly from the brain.
This discovery is likely to help create a new type of prostheses that are controlled by signals sent directly from the brain. They will be much more sensitive and functional than all current models, Oxford neuroscientists conclude.
The details of the study are described in a scientific article published in the eLife publication.