Brain swapping comes of age

For more than two decades, Evan Balaban has honed his skills at manipulating embryonic tissue samples using tiny instruments of his own making. He can cut a small access window into a quail's egg, and using a scalpel no wider than a human hair, excise a few hundred thousand cells from the bird's developing central nervous system. This is only the first step of the intricate process required to place this minuscule brain into another animal's head. Some of these surgeries end in untimely death for brain-transplanted embryos, but Balaban says he has elevated the typical survival rate from less than 20% to more than 60%. That was unimaginable in the 1950s, he says, when success was more along the lines of one or two in 1,000, and some researchers "were doing this with piano wire."