Jorge Luis Borges was a literary neuroscientist, and Gabriel Garcia Márquez described the symptoms of semantic dementia before they were recognized in neurology.
I posted a while ago on some 'philosophy of mind' connections in two of Ian McEwan's novels. ManWithoutQualities recommends two novels that concern recent cog-sci work on consciousness, and there was this post last fall on "the rise of the neuronovel."
There might be something faddish about more recent neuro-lit, but if it leads authors to engage with old philosophical concerns in their new, souped-up neuro form (such as determinism), that's all to the good.
Incidentally, Jonathan Bennett has posted his new translation of de la Mettrie's Man a Machine.
Update (Feb. 11, 2010): MTB reminds us of an earlier book on this theme, Jonah Lehrer's Proust Was a Neuroscientist, about which MTB has several posts.
This song by Raffaella Carrà bears little relation to the rest of this post, except that it exemplifies (for me at least) an interesting psychological phenomenon, which has been dubbed the 'earworm'.