One of the conceits of my world is that the brain takes advantage of some physical processes we don't fully understand resulting in an incorporeal brain-like organ called the Yau-body. Fairly early vertebrates evolved the capability to connect to an parallel incorporeal realm and grow structures there that supplement the brain. Early on, this was fairly simple and just enabled better proprioception by simulating a simple model of the physical body. In higher mammals and especially primates, this process is much more robust, involves more parts of the brain, and results in almost an entire duplicate of the most of the brain's state stored in the incorporeal Yau-body. In humans, comparing the state of the physical brain and it's incorporeal duplicate is the primary way in which consciousness emerges. Naturally, this process also results in some more sci fi stuff, but for this question let's focus on consciousness and neuroanatomy.
Assuming all that, what parts of neuro-anatomy are most involved here? Here are the requirements as I see them.
- Something phylogenetically old needs to be involved. There should be something deep down in the lizard brain that we share with early vertebrates that is the core of this system.
- The advanced thinking/reasoning/language parts should not be the primary drivers here, but part of this system should be in regular contact with those parts. Perhaps acting as a sort of information hub for them.
- Activity in the related regions should be correlated with attention, arousal, or the sense of self when studied.
What brain parts and processes should be involved here? To be clear, I don't plan on getting deep into the weeds of neuroscience in the primary text, these extremely narrow details will be used only in some optional in-universe diagrams meant add verisimilitude.