| Following peripheral neural injury such as
amputation, reorganization of the central nervous system takes
place even though it is still fully intact, suggesting the
importance of afferents and efferents in shaping how the nervous
system behaves. Somatosensory reorganization after amputation
has been shown to involve a loss of cortical representation
of the detached limb and takeover by neighboring cortical
representations of intact areas. However, it is unclear what
would happen if the cortical area controlling the amputated
limb is given a new target muscle to control. In our study,
upper-extremity amputees underwent targeted reinnervation
(TR), a surgical procedure that reroutes residual nerves from
the lost limb to alternative denervated muscle groups. Essentially,
TR provides both re-afferentation and re-efferentation of
the cortical region that used to control the amputated arm.
Our results show that targeted reinnervation can cause further
changes in cortical reorganization to occur after amputation
when cortical areas are re-efferented with a new target muscle.
We are currently working to see whether these changes cause
cortical activity controlling movements of the phantom limb
to more closely resemble activation patterns of the intact
limb.
Understanding how sensorimotor reorganization can change
after procedures such as targeted reinnervation surgery can
expand the possibilities for people with amputations to regain
lost functions and interact with their environment. These
experiments are intended to provide a theoretical basis for
the development of novel prosthetics such as a Neural-Machine
Interface (NMI) that may take advantage of the brain's inherent
plasticity in order to restore movement functionality following
amputation.
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