I wouldn't try to limit it to only one cortical region, but the brain is contains about 88 billion neurons connected to each other by 100 trillion synapses. We operate in 3D (+time) world while brain could easily be thought of as an extremely high dimensional structure, which gives rise to countless rhythms and patterns.
It's clear that DMT changes the way the brain processes information. The real question is why should any recognizable structure emerge in such a short time window, why should it be so clear, why is it seemingly higher dimensional than our serotonin-induced hallucination we call consensus reality, and most of all why can we interact with seemingly discarnate entities, and why are so many different types of entities.
I think it is entirely possible that there are fields of information that our 21st century physics hasn't detected yet. There is so much we humans don't know, and there is absolutely no need for arrogance. We don't know and that's part of the fun!
Andrew Gallimore has a lot of good ideas about this, check out his website if you're interested
www.buildingalienworlds.com