Continuing to counter the dogma that once brain cells give out, they’re gone forever, new evidence shows that newly created neurons may provide hope for treating a wide variety of disorders. Embryonic stem cells have been shown to restore movement after paralysis. And with genetic engineering, stem cells can act as sophisticated protein delivery systems. Scientists have used them to deliver GDNF, a factor to aid in the survival of neurons targeted by Parkinson’s and Huntington’s diseases. Another team has used them to seek and destroy brain tumor cells. And a Norwegian group has proved that even in adults, neural stem cells have the power to become functioning neurons.