[Royce]

So I had a conversation with a guy who mentioned something peculiar indeed. The gist of it was that you could seperate the brain via surgery into two lesser connected halves, where each half is its own consciousness. I think this guy heard this from Sam Harris.

So if the brain can contain a consciousness which is not "yours", then who is to say how many "pockets of awareness" might exist in one brain all the time? If you aren`t conscious of them how could you ever know? They would coexist just like the two hemispheres of a split brain patient.

You might have heard the idea that when a person is hallucinating an "entity" might speak to them. Now this could just be one part of the brain talking to another part of the brain. This is a clumsy description, but it is more likely to the point than it being a spiritual entity making contact with you.

This entity may indeed be originated inside your own skull, but we can not rule out the possibility that this entity could be an independent consciousness. If this is true then certain altered states of consciousness may be a "blurring of the lines" between different instances of consciousness in one`s brain. If it is indeed possible to contact independent consciousness within one`s  own self, this would seem like something we should come to terms with.

For all we know, interactions between conscious "spirits" in altered states was the norm throughout our evolution, and only recently have we made the switch to individual selves located in our language centers.

Perhaps when one takes DMT and has the impression of their individual consciousness breaking through into a larger space inhabited by a proliferation of alien consciousness, this is literally what is happening within the brain. Perhaps the altered state brought on by DMT somehow temporarily erases the separation between "your" consciousness and all the other consciousness present in one`s brain.

[Madness]

In the first paragraph you're talking about a radical, still somewhat employed treatment for severe epilepsy. Because epilepsy occurs when an action potential started in one hemisphere triggers an overload of firing in the other, scientists severed the corpus callosum, the tract of white matter which connects the two halves. This resulted in "split-brain" (love science names ).

The most dramatic evidence of this is when patients are shown different images to each eye. When asked to describe what they saw (in which case they told the researchers what they'd seen - I believe - with their right eye, as based on contralateral function), they'd describe the picture/object. However, when they're ask to point to the object they've seen (I believe with their left arm, because the right hemisphere appears to only either maintain a very limited linguistic function - as opposed to none at all - or devotes compensatory space to that role when the left hemisphere is damaged), patients point to the picture/object seen with their left eye.

On the topic as a whole, it's been suggested that mushrooms work by shutting down the intracorticol integration and dreams are supposed to be a result of similar processes of sleeping.

Also, as I've been dialoguing and formulating with my philosophy of mind professor this semester and the consensus among a great deal of high-minded thinkers is that unconscious/zombie/whatever things underlie consciousness while also constituting that conscious.