There is no evidence for any neurochemical basis, as my follow up post later in the thread explains. It’s purely in the realm of psychedelic lore, anecdotal observation, and weak psychological surveys on testing participants. In other words, it is fringe science. There is simply no way to test for it nor to prove these stories are anything other than stories. The point is that these are examples of the Platonic forms and archetypes found not just in the experiences themselves, but also in the types of substances that are used. You may want to check out Shanon’s book "Antipodes of the Mind: Charting the Phenomenology of the Ayahuasca Experience" which goes to great lengths to document these archetypes. In this instance, Shanon is arguing that ayahuasca has the form of the "jungle", and the user will see snakes, jaguars, vines, etc. as part of this experience. He and others argue that this is embedded into the drug as a form of information, but there’s no way to substantiate this or any other claim using the scientific method. Narby made similar claims, and was widely ridiculed for them. Previously, and many decades before, Leary, Watts, and many others argued that the roots of religious forms and symbols could be found within the drug itself. Watts gives an exceptionally illustrative description of how Hinduism, the world’s oldest religion, seemed to be encoded in the experience.
This all came together as something called the entheogenic hypothesis. It is often used to explain the connection between the evolution of religion and the purported sacraments that may have been used in formal rites. The Eleusinian Mysteries is often referenced as an example. Campbell’s formulation of the "Hero’s journey" is very often seen as a general archetype for the user of these substances in its synthesis of comparative literature (which features these forms as archetypes) and mythology which also translates to religion itself. In Campbell’s formulation, the "boon" that is brought back from the hero, is overlayed and represented in the entheogenic hypothesis as the very informational content that the psychonaut is able to retrieve from the experiences. McKenna often interpreted this as the "logos" but in a more secular context. Lilly and others heard distinct voices giving them instructions. Shanon and others revisited the Abrahamic stories and posited that these voices giving people instructions were equivalent to what ancient people imagined as the voice of god. Still others, like Julian Jaynes, interpreted this idea in a secular way, seeing it more as a story that explains our transition from partial to full consciousness. More recently, the writers of Westworld took a lot of these ideas and applied them to AI, in an attempt to explain how consciousness could eventually emerge again as AGI.