Professor John Lorber ... was not jesting totally when he addressed a conference of pediatricians with a paper entitled Is your brain really necessary?" "There's a young student at this university," says Lorber, "who has an IQ of 126, has gained a first-class honors degree in mathematics, and is socially completely normal. And yet the boy has virtually no brain." The student's physician at the university noticed that the youth had a slightly larger than normal head, and so referred him to Lorber, simply out of interest. "When we did a brain scan on him," Lorber recalls, "we saw that instead of the normal 4.5-centimeter thickness of brain tissue between the ventricles and the cortical surface, there was just a thin layer of mantle measuring a millimeter or so. His cranium is filled mainly with cerebrospinal fluid." Startling as it may seem, this case is nothing new to the medical world. A substantial proportion of patients appear to escape functional impairment in spite of grossly abnormal brain structure. Lorber concludes from these observations that "there must be a tremendous amount of redundancy or spare capacity in the brain, just as there is with kidney and liver." He also contends that "the cortex probably is responsible for a great deal less than most people imagine. For hundreds of years neurologists have assumed that all that is dear to them is performed by the cortex, but it may well be that the deep structures in the brain carry out many of the functions assumed to be the sole province of the cortex."