Transplanted neurons grown from embryonic stem cells can be directed not only to become specific brain cells, but to link correctly into the brains of young animals, a team of neuroscientists led by James Weimann of Stanford Medical School has found.

For example, cells transplanted into the visual cortex reached two deep brain structures called the superior colliculus and the pons, but not to the spinal cord; cells placed into the motor area of the cortex stretched into the spinal cord but avoided the colliculus.

They will now explore whether the same results can be achieved in adult animals and, ultimately, humans.They also hope to understand how the transplanted cells “knew” to connect in precisely the right way, and whether they can generate the right behaviors, such as vision and movement.