What brain parts and processes are most plausibly able to a second incorporeal brain-like organ?

Question

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.

Answer 1

Psychological science major here (thesis in neuroscience).

You're pairing function with structures, but the brain is more complex than that. If cognition is a commodity, then it is the product of a global economy recruiting simpler resources from all over. Just like how an iphone might be misunderstood as being built in the store you purchased it at, it's easy to think that the neurological operation is reducible to a single place of manufacture in the brain.

With this in mind, if I were you I'd scrap or modify trying to have an explicit function attached to the organ(s). They are just another link in the supply chain. Assuming a material view, the brain is already fully functional as is, so does not need any more modules to achieve functions (attention, arousal, and sense of self)it already performs unless you enhance them in some way (this may already be your intention). Rather, they would perform a particular operation that modifies cognitive operations somehow.

I would take a step back and instead of starting from cortical structures, I would start from the connective pathways that facilitate communication between both existent and fantastical structures. Something like the corpus callosum and other mylinated white matter pathways but instead of communicating between hemispheres, it communicates semi directly between distal areas of the brain by avoiding corporeal constraints (such as sending visual information straight from the retina to the occipital lobe, or straight from occipital to motor and central executive processes). This would give immediate fitness improvements by improving reaction time.

Once there's a pathway set up with a function, that pathway is also subject to natural selection, including the possibility of incorporeal structures evolving that have different properties (and therefore different potential outputs) than corporeal anatomy.

Another possible perk of incorporeal brain anatomy is that it could circumvent gyrification and other processes that happen in utero. The brain has to grow from a blue print which comes with structural limitations (think the difference between a prefabricated shelter and a normally constructed building).

If you want the evolution of brains to stay similar to modern brains, you probably want an additional cost to this sort of thing, probably increased energy use, so that the course of evolution doesn't radically alter the brain foundations. Civilization would look a lot different if we could all tereport everywhere and didn't need roads or doorways.

Answer 2

In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you. John 14:2

The world is full of unseen dimensions and energy planes. Our physical beings inhabit one both others are accessible to us. Just as our brains are divided into a right and left hemisphere which concern themselves with intuition and reason, humans in your world have a third mind which concerns itself with these unseen worlds and the powers and presences that manifest therein.

This ability would have clear evolutionary benefit if forces chiefly operating on these planes could affect the physical plane which our bodies inhabit. Disruption of earth energy could be a harbinger of impending disaster, and forwarded creatures seek shelter. Psychic energies stemming from the mass mind of many individuals can be better apprehended and understood. The limits to this are the imagination of the author and the potentially limitless hidden worlds accessible to our third mind.

The nice thing for a fiction is that from the perspective of the third mind you can riff on well trod themes involving the right and left brains and their division of labor and specialties without falling into cliches or established camps of thinking as regards our divided consciousness. That is what science fiction does best.

You can also tap into new age type thinking about these various dimensions for your point of view - my quote at the top is Jesus, but he was quoted in the context of a chapter on the many energy dimensions around us in the book Ascension Magick. The author deals with these unseen realms and how we can access and understand them. Possibly with a third mind? I have not read the whole thing.

Answer 3

A second brain already exists...probably. Ever have a "gut feeling" about something?

The enteric nervous system (ENS) is known as the "second brain" or the brain in the gut because it can operate independently of the brain and spinal cord, the central nervous system (CNS). It has also been called the "first brain" based on evidence suggesting that the ENS evolved before the CNS.

While the ENS and "gut brain" already exist it is not very well understood, you could make it more established/understood/dominant in your world. It's already thought to affect mood and general well-being.

I could see it being the link to your altbrain and because it's not really understood you could get away without having to name folds in the headbrain that would be a bit harder to suspend belief for. In your brainbuilding you could have it have a more pronounced effect or leave as is and simply have the gutbrain be the connection to your altbrain. Because ENS is theorised to have developed before the CNS, you could also include other species in your brainbuilding.

Answer 4

Plausible enough to suspend disbelief? Should I remove any of these parts or get some other parts involved?

I'm going to do a brief frame challenge here. You're asking a very narrow question, which is 'which parts of the brain being named will help suspend disbelief about my magic/sci-magic system'. In general belief is going to be suspended based on complex factors largely related to your presentation in a number of ways. Perhaps your presentation will be generally superior if you feel that the neuroscience of your brain/magic connection is particularly on-point. But putting that aside for a moment, I would suggest that a better question might be to ask how you can increase the verisimilitude of this situation in multiple ways.

Things like 'intentionally making the neuroscience side of this magic system messy in a real-world evolutionary sort of way' may serve your purposes better than naming one specific part of the brain over the other. Having things loop in and out of this other dimension and be used for all kinds of weird things some of which are defunct or not really applicable to the modern creature will help sell that part of it.

In other words I suggest branching out somewhat from 'which part of the brain' and rather looking at making it a complex system of interaction with the brain. This helps in several additional ways, not least of which that it's far less confusing for a reader to hear an explanation of a system described as complex than a bunch of words and terms a layman does not understand.