Over at Neurophilosophy Mo has a great article on the case of Phineas Gage. Gage was a 19th century railroad worker who had a 3 foot long 1+ inch wide tamping iron blasted through his skull in a dynamiting accident. Not only did he survive, but he lived 13 years before dying of complications arising as a result of epileptic convulsions.
The most amazing thing about the accident was the effect it had on Gage's personality:
"Gage did, according to Harlow, retain "full possession of his reason" after the accident, but his wife and other people close to him soon began to notice dramatic changes in his personality. It wasn't until 1868 that Harlow documented the "mental manifestations" of Gage's brain injuries, in a report published in the Bulletin of the Massachusetts Medical Society:
His contractors, who regarded him as the most efficient and capable foreman in their employ previous to his injury, considered the change in his mind so marked that they could not give him his place again. He is fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint of advice when it conflicts with his desires, at times pertinaciously obstinent, yet capricious and vacillating, devising many plans of future operation, which are no sooner arranged than they are abandoned in turn for others appearing more feasible. In this regard, his mind was radically changed, so decidedly that his friends and acquaintances said he was "no longer Gage."
This has dramatic implications for concepts of self and soul. I the soul is a thing apart from the brain, then how does one explain a change in personality from damage to the brain. It is especially stark here since Gage did not lose any physical function. He simply became another person.
Food for thought.