The Mind’s Map of the Physique Is Surprisingly Secure—Even after a Limb Is Misplaced

The Mind’s Map of the Physique Is Surprisingly Secure—Even after a Limb Is Misplaced

By Katie Kavanagh & Nature journal

A brain-imaging examine of individuals with amputated arms has upended a long-standing perception: that the mind’s map of the physique reorganizes itself to compensate for lacking physique elements.

Earlier analysis had instructed that neurons within the mind area holding this inner map, referred to as the first somatosensory cortex, would develop into the neighbouring space of the cortex that beforehand sensed the limb.

However the newest findings, revealed in Nature Neuroscience on 21 August, reveal that the first somatosensory cortex stays remarkably fixed even years after arm amputation. The examine refutes foundational data within the subject of neuroscience that shedding a limb leads to a drastic reorganization of this area, the authors say.

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“Just about each neuroscientist has learnt via their textbook that the mind has the capability for reorganization, and that is demonstrated via research on amputees,” says examine senior writer Tamar Makin, a cognitive neuroscientist on the College of Cambridge, UK. However “textbooks will be improper”, she provides. “We shouldn’t take something without any consideration, particularly in the case of mind analysis.”

The invention might result in the event of higher prosthetic gadgets, or improved remedies for ache in ‘phantom limbs’ — when folks proceed to sense the amputated limb. It might additionally assist scientists working to revive sensation in individuals who have had amputations.

Mapping cortical plasticity

Examine first writer Hunter Schone, a neuroscientist on the College of Pittsburgh in Pennsylvania, says that earlier reviews from some folks with amputations had led him and his colleagues to doubt the concept that the mind’s map of the physique is reorganized after amputation. These maps are liable for processing sensory data, akin to contact or temperature, at particular physique areas. “They might say: ‘I can nonetheless really feel the limb, I can nonetheless transfer particular person fingers of a hand I haven’t had for many years,’” Schone says.

To research this contradiction, the researchers adopted three individuals who have been on account of bear amputation of one in every of their arms. The workforce used useful magnetic resonance imaging (fMRI) to map the cortical representations of the physique earlier than the surgical procedure, after which after the amputation for as much as 5 years. It’s the first examine to do that.

Earlier than their amputations, individuals carried out varied actions, akin to tapping their fingers, pursing their lips and flexing their toes whereas inside an fMRI scanner that measured the exercise in several elements of the mind. This allowed the researchers to create a cortical ‘map’ displaying which areas sensed the hand. To check the concept that neighbouring neurons redistribute within the cortex after amputation, in addition they made maps of the adjoining cortical space — on this case, the half that processes sensations from the lips. The individuals repeated this train a number of instances after their amputation, tapping “with their phantom fingers”, says Schone.

The evaluation revealed that the mind’s illustration of the physique was constant after the arm was amputated. Even 5 years after surgical procedure, the cortical map of the lacking hand was nonetheless activated in the identical manner as earlier than amputation. There was additionally no proof that the cortical illustration of the lips had shifted into the hand area following amputation — which is what earlier research instructed would occur.

Makin says their examine is “essentially the most decisive direct proof” that the mind’s in-built physique map stays secure after the lack of a limb. “It simply goes towards the foundational data of the sector,” she says.

Solaiman Shokur, a neuroengineer on the Sant’anna College of Superior Research in Pisa, Italy, says he was stunned to see the proof proven “in such a transparent method” and that the outcomes “contradict one thing that’s believed within the subject, and accomplish that to some extent”.

Implications for analysis

Giacomo Valle, a neuroengineer at Chalmers College of Expertise in Gothenburg, Sweden, praised the examine’s methodology and says it “places a closing dot — or conclusion — on the controversy” in regards to the mind’s map of the physique following amputation. “That is vital proof,” he provides.

He says that the findings might have implications for analysis on prosthetic limbs which can be managed via mind–pc interfaces implanted within the somatosensory cortex. The data is related to the recruitment of volunteers in scientific trials of such gadgets and for potential individuals who would possibly profit from mind–pc interfaces, he says.

The examine authors be aware that their findings additionally clarify why remedies for phantom limb ache geared toward ‘reversing’ reorganization within the mind’s map have proven restricted success. “Researchers could have missed the profound resilience of cortical representations,” they write.

This text is reproduced with permission and was first revealed on August 21, 2025.

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