u/troll_khan

We are likely born without a strong sense of "I." The Default Mode Network is basically the system that creates the feeling of a continuous self, but when we are born, it is not fully developed. This may explain why little kids (until around age 4–5) and baby animals seem to behave better than their adult versions. Since they don't have this constant mental model of "me" running in the background caused by the DMN, what is left is just experience itself and relaxation of separation and that looks very similar to what many traditions describe as love or unity.

Around age 5 or so, the DMN becomes developed enough that theory of mind emerges, and our sense of separation from the rest becomes much stronger. The "dark night of the soul" could maybe be understood as a sudden collapse of this system after the DMN has been working in overdrive for so long. People who go through this experience often start becoming more spiritual, living more ethically, having less inner conflict, and practicing meditation. All of these things weaken the Default Mode Network.

Meditation may also weaken it not just through changes in brain activity but by also causing the body to produce DMT. We know that people who try DMT report ego dissolution, infinite consciousness, unity, and other extraordinary experiences. It seems that heavy use of DMT can temporarily disrupt the normal structure of the Default Mode Network.

But then the brain rebuilds the self-model (the Default Mode Network) again mostly within a few hours and more completely over a few weeks. That may be why enlightenment does not seem achievable through psychedelic use alone. You can only truly weaken the Default Mode Network through long-term transformation: meditation, ethical living, and changing the way you relate to experience. Otherwise, with external substances, the brain simply rebuilds the structure again.

The structure of your Default Mode Network at the moment of death could then become the launching point of your consciousness for its next experience. If this theory is true, then what needs to be discovered are techniques that can permanently weaken the brain's Default Mode Network and the sense of a separate self caused by it.