Explanation to ‘Ghost Member’

A research team formed by members of the National Institutes of Health of the United States and the University of Cambridge has been able to demonstrate a Amazing aspect of the human brain. Contrary to what was believed, this study has shown that The brain keeps its “body map” unchanged Even after losing a limb. That is to say, brain activity after an amputation does not changeand the brain seems not to know that the amputated member is no longer there.

The finding, Posted in Nature Neurosciencecontradicts the classical idea that brain areas are reorganized to compensate for absence. Thus, the Sensation of ghost, tingling or itching pain that many people with amputated members claim to have After losing this limb.

The work compared the brain activity of three people before and after amputation From one hand, and the clarity of the results not only clears some doubts about the origin of the ghost pain, but also offer New opportunities to improve prostheses control advanced

Brain maps remain intact

In the Somatosensory cortex of the brain, Each part of the body has a region assigned. During the investigation, brain scanners were carried out to map the hand and lips, since these two areas are very close to the brain. It was observed that, after amputation, The representation of the hand continued to activate almost unchanged.

The neuroscientific of the University of Cambridge and main author, Tamar Makin, stressed that They did not expect such obvious results: “Due to our previous work, we suspected that brain maps would remain largely unchanged, but The degree to which the map of the missing limb remained intact has been amazing. Given that the somatosensory cortex is responsible for interpreting what happens inside the body, it seems surprising that it does not seem to know that the hand is no longer there. ”

The finding was so clear that, according to the researchers themselves, They would not have been unable to distinguish whether a map belonged to the previous or subsequent period to the amputation if they did not know the registration date. Only an artificial intelligence algorithm managed to differentiate which finger “ghost” was moving in each case. Hunter Schone, first author and member of the University of Pittsburgh, summarizes it: “We do not observe any indication of the reorganization that is supposed to occur According to classical thinking. Brain maps remained static and unaltered. ”

An explanation to the pain of the ghost member

Schone explained the fundamental issue by which the phenomenon already known as “ghost pain”but clarified that, thanks to the study, they have been able to elucidate some details: “The remaining parts of the nerveseven inside the stump, they are no longer connected to their terminal receptors. They are completely disconnected from sensory receptorss that have transmitted constant signals. Without a terminal receiver, The nerves can continue to growforming a thickening of nerve tissue and sending confusing signals to the brain. ”

In addition, the researchers verified that The limits of brain maps are not rigidwhich means that The same area can participate in several sensory functions. The study also included 26 people with long -term amputationson average of more than two decades, in whom The same pattern was observed: The brain representations of the lost limbs remain stable over the years.

New perspectives in surgery and prostheses

Clinical implications are promising. Schone said the study helps to remember that “The brain clings to the body”even after losing a limb: “The most promising therapies imply rethink how amputation surgery is really performedfor example, grafting the nerves in a new muscle or skin, so that they have a new place to adhere. ”

Of the three patients of the study, One underwent this type of advanced intervention and stopped suffering painwhile the other two, operated with standard techniques, continue to experience discomfort in the ghost member. Along the same lines, the researcher of the National Health Institutes, Chris Baker, stressed that, If the brain was reconfigured after an amputation, these technologies would fail: “If the brain area that previously controlled the hand was now responsible for the face, these implants would simply work. Our findings offer a true opportunity to develop these technologies now.”

A concept of reorganization that must be reviewed

Work has also aroused interest in the Spanish scientific community. Juan de los Reyes Aguilar, responsible for the Experimental Neurophysiology Group at the National Hospital of Paraplegics, valued that these data can contribute to “decipher and even redefine the complexity of the reorganization phenomenon cortical”.

According to this specialist, the results suggest that It is not enough to think of a mere expansion of neighboring areas after an injury: “Given the perceived pain data shown in the article, it could be discussed that the concept of cortical reorganization after amputation or core injury is something more complex of what is currently in the literature, which is reduced to an expansion of the activated cortical area, and could focus on alterations of sensory perception. ”