A new study has revealed the remarkable plasticity of the young brain, showing that children born with a congenital upper limb difference develop widespread changes in their brain’s body map to support everyday activities.
The research, led by teams at the University of Cambridge and Durham University, used functional magnetic resonance imaging (fMRI) to examine brain activity in young children. The findings show that the brain reorganises itself from an early age, allocating resources to other body parts to compensate for the limb difference. These changes appear largely stable into adulthood.
The somatosensory cortex contains a map of the body, known as the sensory homunculus, where different regions process sensory input such as touch, temperature, pain and body position. Although early brain plasticity is well-recognised, much of the evidence has come from adult studies, leaving open questions about when and how reorganisation occurs in childhood.
Imaging young children can be difficult because movement during scans may distort results. To address this, researchers developed a child friendly protocol. The study included 16 children aged 5–7 with congenital upper limb difference, typically with the arm ending below the elbow, as well as 21 age matched children without limb difference. Adult groups with and without similar differences were also included for comparison. Participants first completed everyday tasks such as opening a jar or unwrapping a sweet so researchers could observe compensatory strategies.
During scanning, children listened to a story about an enchanted forest where butterflies had become invisible. They wore custom devices developed at EPFL in Switzerland on the chin, arm, torso, leg, foot, thumb and forehead. The devices fluttered to simulate butterfly wings touching the skin, allowing researchers to map brain responses to stimulation of different body parts.
The findings, published in Nature Communications on 24th February 2026 showed that in children born with one hand, the brain region typically devoted to the missing limb instead represented multiple other body parts. The reorganisation extended beyond the hand area, with the broader body map shifting towards that region.
The brain devoted more resources to body parts used in compensatory strategies, effectively repurposing territory typically allocated to hand function. Individual brains also showed tailored adjustments reflecting each child’s unique behavioural strategies.
Professor Tamar Makin from the MRC Cognition and Brain Sciences Unit at the University of Cambridge said: “These kids have to figure out how to adapt to a world that’s been designed for people with two hands, and they come up with unique and interesting behaviours, using lots of different body parts. This raises a really interesting question about how their brains adapt to support this unusual journey.”
“Surprisingly, the brain seems to be already set up for this journey. Very early on we see more brain resources devoted to other body parts, that they’re using territory designed by evolution to support hand function. Their entire body map is shifted and changed from an early age. On top of that, in each child’s brain we see bespoke tailoring at a smaller scale based on the strategies that they’ve evolved.”
A computational model indicated that the changes are not explained solely by “use it or lose it” principles. Instead, they are also driven by homeostatic plasticity, which regulates neural activity to maintain stability and prevent extremes such as inactivity or overexcitation.
Dr Raffaele Tucciarelli from the MRC Cognition and Brain Sciences Unit said: “Although we found changes in the brain relating to behaviour – how a child compensates for their limb differences – we saw much wider changes going on due to this homeostatic plasticity. This mechanism is there to maintain stability in firing rates in the brain, to ensure brain tissue doesn’t stop working from too little activity or cause a seizure from too much activity.”
“This was really surprising for us. Even though we knew these regulatory processes existed, we don’t tend to think of them in relation to reorganisation at this large scale, because we tend to think of this reorganisation happening as result of behaviour.”
Comparisons with adults showed that early brain changes remain largely stable, even though adults tend to rely more heavily on their remaining arm.
The study collaborated with the charity Reach, which supports families and young people with upper limb difference helped recruit participants.
Professor Dorothy Cowie from the Department of Psychology at Durham University said: “A lot of the parents we meet have had very little information about their child’s limb difference and how it will impact their daily life, let alone what’s happening in the brain.”
“Our research shows how adaptable the human brain is, and we hope this is reassuring. Their child’s brain is wired differently to their two-handed peers so that it can support their different approaches to doing things, such as using their legs or torso to help open a jar. Their child will figure things out in their own way, and their brains will support these developing behaviours.”
Gemma Lonnon’s son, Noah, now 11, participated through the BOLDKids programme. Gemma said: “We first met the BOLDKids research team at a Reach family weekend in 2019. They were conducting practical tests with children who have upper limb difference, and we thought Noah, who was five at the time, might enjoy taking part.”
“Since then, BOLDKids have invited Noah to take part in other studies including an online problem-solving test designed to feel like a video game and this more in-depth study which included practical problem-solving tests and a brain scan. Noah really enjoyed taking part in this research. His favourite part was going in the MRI machine and seeing pictures of his brain!”
“As a family, we wanted to take part to understand how Noah’s brain adapted to his limb difference. Over the years we have seen that Noah adapts quickly to problem solving and everyday tasks and activities. He comes up with practical solutions to situations that we don’t see.”
“Taking part was important to us. It is fascinating to see how children like Noah develop unique skills to overcome challenges. We’re proud to be part of something that could help other families too.”
Steve Haynes from Reach said: “At Reach Charity we’re really grateful this research has been undertaken. The findings reinforce what many Reach adults have long suspected: that our brains can feel like they’re wired a little differently. This study highlights the unique strengths that those with upper limb difference can bring to a world that is often not designed with them in mind.”
The research was supported by the Wellcome Trust, the Medical Research Council, and the Czech Science Foundation. Some work by Professor Makin and Dr Tucciarelli was conducted at UCL.