The zipheads were crippled with a weaponized virus that turned them all into autistic savants. The virus was somewhat magnetic, and using MRI like technologies, they could target specific parts of the brain to be affected to lesser or greater degrees. It's been awhile since I've re-read it, but "focused" was the propaganda label for it from the monstrous tyrannical regime that used it to turn people into zombies, no?
Not zombies, but loving slaves. People able to apply all of their creativity and problem–solving skills to any task given to them, but without much capacity for reflection or any kind of personal ambitions or desires.
