I was actually trying to source brain originally and even around here I haven't found any. Hearts, livers, yeah. Brain, no. Interesting that it was so expensive; I guess because he'd have to scoop the brain out of skulls?>>1773644
That was my worry too, animal diseases and stuff like brain parasites. Despite it being rare, I remember hearing (a news story of) one old guy finally dying from eating cooked squirrel brain, something that was a traditional meal in his family. No one else ever had it happen in his family. The thing that freaked me out the most is that while rabies can be cured if caught early, even if they have to do a lot of work to make sure you don't die, the brain parasite was unable to be cured. Nothing to do. Even if it's rare, even if I'm not eating it, I'm not taking the chance; I don't need any more risks of dying. Also I like headshots on squirrels, so the brain is already damaged. I know it's rare, I know it's unlikely I'll ever shoot, work on, or even see a squirrel that is affected by it in my life, but fuck the chance.
Also, that is the original method of tanning as far as I know. This is, of course paraphrased, but someone once told me that the Native Americans used to and still do brain tan animal hides, "Every animal has enough brain to tan its own hide" (though oddly, apparently Buffalo are the exception, at least in North America).