In 1980, Roger Lewin published an article in Science, "Is Your Brain Really Necessary?",[1] about Lorber studies on cerebral cortex losses. He reports the case of a Sheffield University student who had a measured IQ of 126 and passed a Mathematics Degree but who had hardly any discernible brain matter at all since his cortex was extremely reduced by hydrocephalus.
David Bowsher, professor of neurophysiology at Liverpool said "Lorber's work doesn't demonstrate that we don't need a brain", and neurosurgeon Kenneth Till said that Lorber is "overdramatic when he says that someone has 'virtually no brain.'" Lorber admitted it later, saying that he "was only half serious", but defends himself with: "I can't say whether the mathematics student has a brain weighing 50 grams or 150 grams, but it is clear that it is nowhere near the normal 1.5 kilograms.". In his later years Lorber expressed great sorrow that more attention had not been paid to his sensational findings.[4]
Couldn't find the whole science article for free, but I managed to get the first page.
The short version is, there have been a significant number of people with damaged brains that function normally.There are even quite a few cases of people with brains 5-10% the normal size that still seem completely normal.
So yeah, turns out that big thing in our heads is mostly for show.
