There is the chemistry induced by the substance, and then there is the cognitive response to the chemistry.
Physiology will vary somewhat from individual to indivdual. Absorption rates and disposition may vary by weight and metabolism, but anyone who ingests, say, 250mics of pure LSD is going to get pretty much the same fundamental chemical load. Much of these compounds (LSD, Psilocybin) goes straight to the midbrain and the Reticular Activating System. The RAS is like a major router from the hindbrain to the cortex and can be alternately excitatory and inhibitory, so some parts of the cortex get turned on while others get turned off. The occipital cortex - the visual cortex at the back of the head - gets excitatory input and begins to fire excessively. This is the foundation for patterns seen with these substances. But the RAS also arcs onto many other cortical areas, like the auditory cortex and higher associative neural tissue. This contributes to the general CNS stimulus that these compounds have - you get turned on, antsy, hyperaware.
However it is very unlikely that you will ever encounter pure LSD, or even LSD-25. More likely you will find something with impurities from the manufacturing process, or something that isn't even LSD-25 (there are many derivatives with differing effects).
Things start to get a bit more complex going from a pure substance like LSD to an organic one like Psilocybin, as delivered by Psilocybe cubensis, the friendly mushroom. Here you have a whole bunch of secondary compounds that make the mushroom a living organism, some of which are a bit toxic. This lends to the death & rebirth experience so common with mushrooms and is, in part, a toxicological response of your entire system to a poison. Also the chemistry of psilocybin, and its metabolite psilocin, is different from LSD and will accordingly distribute itself in the brain a bit differently. It's like a program that will run on the same operating system but will modulate it in a different manner.
So, this has just been a very topical overview of the chemistry. Each hallucinogen has a basic program that it's going to run in your brain. The brain in turn will have its activity modified which will impact higher cortical regions (your mind) as well as the rest of your nervous system (your body). Now, the really interesting part is how your mind tries to cope with the situation, overlaying patterns on excess firing in the visual cortex, invoking memories and archetypes, dissassociations from the body, a feeling of connectedness, as well as any myriad of variations on the above. Hence, the experience of one is not likely to be that of another.
However, as an interesting aside (forgive my ramble but this is a topic near and dear to my heart), there have been anthropological studies with the complex of compounds known as Ayahuasca which seem to imply that this particular batch of chemistry holds certain archetypes. In other words, aside from simply modifying neurochemistry, it also seems to modify mind in very distinct, reproducible ways. An Amazonian native taking Ayahuasca sees visions of snakes, jungles, and jaguars. A resident of Los Angeles taking ayahuasca sees snakes, jungles, and jaguars. An Inuit taking ayahuasca sees snakes, many trees, and "large cats" (having no conception of Jaguars). So it may be that strong cultural associations with specific compounds actually impart meaning into that space, adding specific content to an otherwise abstract experience. Therefore, there may actually be cognitive similarities between the trips of one LSD user and another. Maybe the peace & love vibe has been irrevocably bound to the LSD gestalt, perhaps like the alien encounter experience seems bound to DMT. This of course lends credence to the notion that these substances are indeed keys to certain experiential models beyond mere chemistry.
But this is getting into a whole nother super-cool topic that I could rant about for days... |
