Brain: Meet Your New Hand

Savage, now 56, presented a rare chance to examine the brain's response to a limb transplant.

Scott Frey, associate professor of psychology, and colleagues seized that opportunity, and used functional magnetic resonance imaging (fMRI) techniques to observe the relationship between Savage's brain and new hand. The results of the study, for which Frey was lead author, appeared in Current Biology last October.

Scientists have long known that, after a limb is amputated, the brain areas that received input from that limb can modify to "communicate" with another part of the body. What they didn't know until recently, however, was whether the brain can adapt back to its original orientation after a successful transplant.

Indeed it can, at least in Savage's case. Four months after surgery, Savage could feel sensation in his palm when it was stroked by a sponge. When fMRI images were taken simultaneous to the stimulation, they revealed activity in the areas of his brain roughly comparable to those of four male control participants when their right palms were stroked.
 
Those areas are also the same ones that would have responded to his original right hand, demonstrating that the hand was "reclaiming" its old territory.

Frey, who is also director of the Lewis Center for NeuroImaging, said the findings were significant because they reveal that brain plasticity can occur not just during the formative childhood years, as was once thought, but also well into adulthood.  

- Amanda Miles