In an email, study author Hunter Schone followed up with these answers to my questions:
What is the significance of the finding?
Many treatments for phantom limb pain are built on the idea that the brain’s map of the missing limb gets scrambled and needs to be retrained. Our results show these maps aren’t broken — so therapies should move away from the brain and instead target the severed peripheral nerves. This result gives us confidence that brain-computer interfaces can reliably tap into a stable source of bodily signals, despite the loss of the sensory input.
Why didn’t we realize this until now?
Most of the evidence came from animal studies. Though, critically, amputated monkeys couldn't describe that they still feel phantom sensations of a missing limb — a subjective phenomenon unique to humans. By following people before and after amputation and tracking how the cortical body map changes, for the first time, we were finally able to see the stark stability of these maps across the amputation.
What is the significance of the finding?
Many treatments for phantom limb pain are built on the idea that the brain’s map of the missing limb gets scrambled and needs to be retrained. Our results show these maps aren’t broken — so therapies should move away from the brain and instead target the severed peripheral nerves. This result gives us confidence that brain-computer interfaces can reliably tap into a stable source of bodily signals, despite the loss of the sensory input.
Why didn’t we realize this until now?
Most of the evidence came from animal studies. Though, critically, amputated monkeys couldn't describe that they still feel phantom sensations of a missing limb — a subjective phenomenon unique to humans. By following people before and after amputation and tracking how the cortical body map changes, for the first time, we were finally able to see the stark stability of these maps across the amputation.