Brain plasticity after a questioning amputation | The doctor’s daily life | Specialties

“It is rare to manage to carry out a study like this”says Christopher Baker. However, head of unit at the National Institute of Mental Health (NIMH) and co-author of a new study on brain plasticity in amputated patients. However, With British colleagues (University College of London, University of Cambridge, etc.). Nevertheless, he managed to demonstrate that cortical reshaping in response to amputation is ultimately much less than what we have believed for several decades. Therefore, To achieve this, they used an unprecedented approach: compare brain activity before and after amputation.

It took them seven years to identify. However, select three patients likely to answer their questions and whose amputation was scheduled. Therefore, The first was amputated following an evolutionary arteriovenous malformation. In addition, The second was to withdraw a sarcoma which has been progressing slowly since 1995. Consequently, It had already undergone brain plasticity after questioning amputation several operations before amputation, which had altered its engine control. Furthermore, Finally. Therefore, the third patient had an extremely rare congenital involvement: Severelle -Martorell syndrome which is characterized by extensive venous malformations, hemangioma, and hypoplasia which can lead to bone destruction and shortening of the limbs.

Gift packaging – Brain plasticity after questioning amputation

According to the article published in Nature Neurosciencea functional MRI was made twice before the operation. in order to map the brain activity launched by various finger movements. More specifically, the researchers asked the three women to pack a gift, then move a single finger. The same examination was repeated four to five times in the five years which followed the amputation. Doling back into the same situation. patients felt finger movements of their ghost member identical to those they knew before amputation. There was little, or even no major change in the pre-and post-extension brain activity. According to the authors, brain plasticity after questioning amputation if the dates of the exams were masked, it was even impossible to distinguish brain maps.

They called on an AI specially trained to distinguish the brain areas assigned to the movement of each finger. Several years after the amputation. the algorithm was always able to know which finger of the ghost member was “stirred”, a sign that the organization of this region of the cortex had not disappeared to control them individually, despite their disappearance.

The researchers also found that the nearby brain circuits associated with the movements of the lips. feet did not migrate to the territory of the ghost member (which had however been in the primates). Additional analyzes comparing their data to valid witness scanners. as well as other studies, have only strengthened their initial impression: the cerebral representation of the member continues.

Rethink the pain treatments of the ghost limb

“For decades. brain plasticity after questioning amputation cortical reshaping in response to an amputation was a typical example of brain plasticity”explains Christopher Baker. The defenders of this hypothesis relied a lot on studies made in the monkey. which showed colonization of the cortical areas dedicated to the somatosensory control of the arm by the neighboring regions, devoted, for example, to the control of the face. But the application to the human being of this theory of remodeling of the primary somatosensory cortex has been the subject of debates. in particular linked to the existence of invasive ghost limb syndrome, which manifests itself in lively, often painful sensations, in a now missing member.

By demonstrating the inertia of the primary somatosensory cortex in human patients. this new study opens the door to an improvement in the understanding of ghost limb syndrome, and invites you to rethink the standard treatment of ghost pain – many of which suppose cortical brain plasticity after questioning amputation reorganization after amputation. These results could also be essential for the implementation of brain-computer interface processing technologies.

“This study reminds us that the brain clings to the missing member. almost as if it was waiting to be reconnected there in one way or another”adds Hunter Schone, first author of the study. “Today, brain-music brain interface technologies, in full development, can work from the principle that brain cartography remains coherent over time. Our data allows us to reach a new border: accessing finer details of hand cartography. such as distinguishing the tip of the finger from its base, and restoring the richness and quality of sensations, such as texture, shape and temperature. »»