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Brain maps Remain Remarkably Stable Years After Amputation, New Research Shows
A groundbreaking study published in Nature Neuroscience challenges long-held beliefs about brain plasticity, revealing that the brain’s maps for hand and lip movements remain surprisingly stable for years after amputation. This revelation has significant implications for the future of prosthetic design and rehabilitation strategies.
For decades, the prevailing theory in neuroscience suggested that when a limb is lost, the brain region dedicated to that limb is “invaded” by neighboring areas, especially those controlling the face. However,this new research,utilizing advanced functional magnetic resonance imaging (fMRI),paints a different picture.Researchers found that despite the loss of sensory input, the brain largely preserves its internal portrayal of the missing hand.
The study,conducted between 2023 and 2025,tracked three adult participants scheduled for unilateral arm amputation over a period of up to five years. Researchers monitored brain activity before surgery, and at regular intervals – 3 months, 6 months, and 1.5 to 5 years post-amputation – using fMRI. They also included a control group of 16 able-bodied individuals and a cohort of 26 chronic amputees for comparison.
“What we found was quite remarkable,” said a lead researcher. “The hand and lip representations in the brain remained topographically stable, even years after amputation.”
The team focused their analysis on the primary somatosensory cortex (S1) and the primary motor cortex (M1), key areas involved in processing touch and controlling movement.They discovered that participants continued to experience phantom limb sensations and could even attempt to move their missing hand. Importantly, these attempted movements were accompanied by muscle contractions in the residual limb, confirming they weren’t simply imagined actions.
The researchers employed sophisticated analytical techniques, including multivoxel analyses using support vector machine (SVM) decoding and representational similarity analysis (RSA), to assess the stability of the brain maps. These methods confirmed that the patterns of brain activity associated with individual fingers could be reliably decoded even after amputation.
Contrary to expectations, the study did not find evidence of significant “invasion” of the hand region by the face. Lip activity in the area previously dedicated to the hand remained within the range observed in able-bodied individuals. While one participant showed a temporary shift in lip-thumb representation at six months post-amputation, this normalized by the five-year follow-up.
The findings suggest that S1 isn’t merely a passive receiver of sensory details, but rather maintains a resilient, internal model of the body. This internal model persists even in the absence of sensory input.this has profound implications for how we approach prosthetic growth and rehabilitation.
“This stability matters clinically,” explained a senior neuroscientist familiar with the study. “It suggests that we can leverage these intact hand representations to improve prosthetic control and develop more effective neurostimulation therapies.”
The study acknowledges certain limitations, including a small sample size and a focus on adult participants.Future research should investigate whether similar patterns of stability are observed in children, who exhibit greater neuroplasticity, and explore how different causes of amputation and rehabilitation approaches might influence brain reorganization. .
The research team hopes to expand their work to include a more diverse range of participants and investigate the potential for targeted interventions to further enhance the stability of cortical maps an
