Short answer: it is a line supposed to interest you in reading the rest of the piece of writing.
When he has a brain, probably form a dead person and he is intersted to disect to see if there was an abnormality that might suggest why they died, or killed themselves.
This is from context, not from understanding the sentence.
Further down in the text it says that he started watching autopsies. It also pspeaks of doing MRIs of brains.
It appears he has an interest in suicides and looking for brain disorders that connect to suicide.
So, rather than brain surgeon it seems he might only do analysis, perhaps after death.
I have not read the whole things, sorry.