The body of the brain’s body is surprisingly stable – even after a lost member

The body of the brain’s body is surprisingly stable – even after a lost member

By Katie Kavanagh & Nature Magazine

A cerebral imagination study of people with amputated arms has turned a longtime belief: that the body’s brain card is reorganized to compensate for the missing body parts.

Previous research has suggested that neurons in the brain region holding this internal map, called the primary somatosensory cortex, would have an affect in the neighboring zone of the cortex which previously felt the member.

But the latest discoveries, published in Nature Neuroscience on August 21, reveal that the primary Cortex Somatosensory remains remarkably constant even years after the amputation of the arm. The study refutes fundamental knowledge in the field of neuroscience only the loss of a member leads to a drastic reorganization of this region, according to the authors.

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“Almost all neuroscientists have learned through their manual that the brain has the capacity for reorganization, and this is demonstrated by studies on amputees”, explains Tamar Makin, principal author of the study, a cognitive neuroscientist of the University of Cambridge, in the United Kingdom. But “manuals can be wrong,” she adds. “We should not take anything for granted, especially with regard to research on the brain.”

Discovery could lead to the development of better prosthetic devices, or improved treatment for pain in “ghost members” – when people continue to feel the amputated limb. This could also help scientists work to restore sensation in people who have had amputations.

Cartography Cortical plasticity

The study of the first author Hunter Schone, neuroscientist of the University of Pittsburgh in Pennsylvania, says that the previous reports of certain people with amputations had led him, he and his colleagues, to doubt that the card of the body of the brain is reorganized after the amputation. These cards are responsible for the processing of sensory information, such as touch or temperature, in specific bodily regions. “They would say,” I can always feel the member, I can always move my individual fingers with one hand that I have not had for decades, “explains Schone.

To investigate this contradiction, the researchers followed three people who were to suffer an amputation of one of their arms. The team used functional magnetic resonance imaging (IRM) to map the cortical representations of the body before surgery, then after amputation up to five years. This is the first study to do so.

Before their amputations, the participants carried out various movements, such as typing their fingers, continuing their lips and flexing their toes inside an irm scanner which measured the activity in different parts of the brain. This allowed researchers to create a cortical “card” showing what regions felt the hand. To test the idea that neighboring neurons redistribute in the cortex after amputation, they also made cards in the adjacent cortex area – in this case, the part which deals with the sensations of the lips. The participants repeated this exercise several times after their amputation, tapping “with their ghost fingers”, explains Schone.

The analysis revealed that the representation of the body of the brain was consistent after the amputation of the arm. Even five years after surgery, the missing hand card was always activated in the same way as before amputation. Nor was there any evidence that the cortical representation of the lips had moved to the hand region after the amputation – this is what previous studies suggested would occur.

Makin says that their study is “the most decisive direct proof” that the integrated brain body card remains stable after the loss of a member. “It goes against the fundamental knowledge of the domain,” she says.

Solaiman Shokur, a neuroengineer at the Sant’anna School of Advanced Studies in Pisa, Italy, says that it was surprised to see the evidence presented “in such a clear” way and that the results “contradict something that is believed in the field, and do it to a certain extent”.

Research implications

Giacomo Valle, Neuroengineer at the Chalmers University of Technology in Göteborg, Sweden, praised the study methodology and says that it “puts an end – or conclusion – on the debate” on the body of the body of the brain after amputation. “This is important proof,” he adds.

He says that the results may have implications for research on prosthetic members who are controlled by brain-manager interfaces established in the Somatosensory Cortex. Information is relevant to the recruitment of volunteers in the clinical trials of these devices and for potential participants who could benefit from cerebral-manager interfaces, he says.

Study authors note that their results also explain why the pain treatments of ghost members aimed at “reverse” the reorganization of the brain card showed limited success. “Researchers may have missed the deep resilience of cortical representations,” they write.

This article is reproduced with permission and was first publication August 21, 2025.

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