This week's New Yorker features an engaging article by Christine Kenneally about hemispherectomy, perhaps "the most radical procedure in neurosurgery." In this procedure, an entire side of the hemisphere is removed as a treatment for cancer or chronic seizures. The incredible thing is that if the hemispherectomy is done when a patient is very young, the remaining hemisphere does double duty and the child often develops normally.
From Half a Brain via Children with half a brain
Half a Brain is Enough is the extraordinary story of Nico, a three-year-old boy who was given a right hemispherectomy to control his severe intractable epilepsy. Antonio Battro, a distinguished neuroscientist and educationalist, describes his work with Nico over several years and explains how a boy with only half a brain has developed into a bright child with relatively minor physical and mental impairment. Eight years later, he runs and plays with only a slight limp. So far, there is no significant cognitive or affective disorder and it appears that Nico's so-called right-hemisphere skills--mathematics, visual arts, and music--have migrated to the left hemisphere. At school, he performs as a child of his age in arithmetic and music; only his draftsmanship and handwriting are poor for his age, but he has not lost his cognitive spatial ability. Battro and his colleagues have been studying and teaching Nico with computers and he is mastering written language with a word processor and is able to make good graphic designs with a computer. Nico performs well above average verbally, a left-brain skill.
This is remarkable. There is lot of things we don't know about the brain and obviously how we learn.