[Sharlin]

Surely the concept itself is sound if you forget the misleading names and the idea of three independent modules? The more ancient parts of the brain certainly are located nearer the brainstem, and the most recent ones near the surface.

Also, even though the brain appears on a high level to function as a coordinated whole, there are certainly situations where, for instance, the ancient FFFF[1] responses compete with whatever the neocortex wants to do. Indeed, there's even a plausible-sounding hypothesis[2] that subjective experience itself arises from conflicts between the different modules.

[1] Fight, flee, feed, reproduce

[2] http://www.rifters.com/crawl/?p=791