Originally posted by Ytse
What's really interesting is that there is this very potent hallucinogenic tryptamine called DMT which is produced by the human body. Some have theorized that NDE's (and some aspects of dreaming actually) may be caused by this particular molecule.Unfortunately it is illegal to use when derived from outside sources (which is extremely weird imo) but the hallucinations can be so intense as to be "true" hallicinations. Unlike the hallucinations one would usually experience with LSD or psilocybin these are more akin to the kind you experience with belladonna poisoning. That is to say, you cannot distinguish reality from hallucination.
we produce something chemically similar to DMT, but there is no real research that shows it plays any role in hallucinations or what not. It might have something to do with dreaming, though now that I'm thinking about it, possibly with our ability to test reality (ie, when we dream outlandish things don't seemed far fetched).
There are brain areas that we can use synthetic drugs to activate that will make a person have an out of body experience, which pretty much proves that they are a construct of our subjective experience and not real. NDEs are best explained by localization of function and anatomy rather than through neuro chemistry.
And with most drugs, a lot of the hallucinations and other things of that nature come from expectation. I took a class about drugs this year, and my best analysis is that the people who have done the research thus far (with some notable exceptions) have no personal experience with the substances. Add that to the fact that many of the underlying neural mechanisms behind hallucinations are not yet understood (which is something I would love to use psychadellics to study) it becomes very difficult to clasify the way a specific drug will affect an individual, until the individual is experienced enough with the drug to remove some of the more cognitive issues associated with the high. This explains the huge variance in behaviour in casual and first time users of a substance versus long term users.