Having something mapped is not the same thing as knowing how it works.

Quite, but the comment I was replying to spoke only of mapping individual neurons and their connections. This has been done, and presumably a lot is known about what they do. But it appears not to be enough. In view of that, what will it really take to do a whole human brain emulation? Until it has been demonstrated in, say, C. elegans, it is so much moonshine.