Isn't that what we practically have from rats? a "subset" of the human brain? I cringe every time I see on some tech/science news some headline: "this is the reason you do this, or you think that", and then reading the study, you find out it was conducted on rats...

If we are extrapolating results from rats to humans, why can't we just simulate a rat brain and avoid torturing more? Probably because rats are cheap, and supercomputers, well, are super expensive.

I don't think it would be difficult to simulate a fully functional rat brain with state-of-the-art technology and bright people.