MedicalResearch.com Interview with:
Sanne Kikkert, DPhil student
FMRIB Centre, University of Oxford
Oxford, United Kingdom
MedicalResearch.com: What is the background for this study?
Response: One of the most mysterious questions about the brain’s ability to adaptively change to new circumstances is: what happens to the brain once a key input is lost (e.g. through amputation)? It has been thought that the hand representation in the brain, located in the primary somatosensory cortex, is maintained by regular sensory input from the hand. Indeed, textbooks teach that any sensory representation in the brain will be ‘overwritten’ if its primary input stops. Following this explanation, people who have undergone hand amputation would show extremely low or no activity related to its original focus in the brain area of the missing hand.
However, we know that amputees often experience phantom sensations from their missing hand, such that when asked to move a phantom finger they can ‘feel’ that movement. We previously showed that we can trace some activity in the missing hand brain area when amputees move their phantom hand. In this study, we were interested in finding how the representation of a missing hand is stored in the brain.
MedicalResearch.com: What are the main findings?
Response: We looked at the brains of individuals who had undergone arm amputation and experienced vivid phantom sensations. We asked them to move individual fingers of their phantom hand in a brain scanner. We used advanced imaging techniques, allowing us to identify representation of individual fingers.
Results showed that the representation of the missing hand persisted even decades after amputation. In fact, the fine-grained finger information still matched well to that of two-handed controls, also tested in the study. Therefore, our results indicate that the brain ‘remembers’ the representation of an amputated hand, long after the sensory input is lost. It does not erase the original function of a brain area, as previously thought.
MedicalResearch.com: What should readers take away from your report?
Response: The brain ‘remembers’ the detailed representation of the individual fingers of a missing hand, even decades after amputation.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Our findings remove a barrier to neuroprosthetics (prosthetic limbs controlled directly by the brain): the assumption that a person would lose the brain representation that could control the prosthetic intuitively. If the brain retains a representation of the individual fingers, this could be exploited to provide the fine-grained control needed.
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Revealing the neural fingerprints of a missing hand
Sanne Kikkert, James Kolasinski, Saad Jbabdi, Irene Tracey, Christian FBeckmann, Heidi Johansen-Berg, Tamar R Makin
University of Oxford, United Kingdom
Published August 23, 2016
Cite as eLife 2016;10.7554/eLife.15292
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