FoundationalConceptsNeuroscience

America. One Amazonian preparation combines a DMT-containing
plant (usually Psychotria viridis) with another plant—the ayahuasca
vine, Banisteriopsis caapi—the presence of which potentiates the
effects of DMT. The combination of these two plants is cooked up to
yield a strong-tasting brew that also goes by the name ayahuasca, as
well as other names, such as yage.
A couple of other related psychedelic chemicals identified from
plants include lysergic acid amide from the seeds of certain morning
glories, and ibogaine from the root of the African plant Tabernanthe
iboga. These plants also have a history of ritual use in shamanic cer-
emonies: morning glories in southern Mexico and iboga in western
Africa.
The substances thus far discussed are sometimes grouped together
as “classical” psychedelics or hallucinogens. Neurochemically, the
classical psychedelics have been found to bind as agonists to various
serotonin receptor subtypes, especially type 2A serotonin receptors
(called 5HT», receptors). Psychedelics also bind to other neurotrans-
mitter receptors, including those for dopamine and norepinephrine.
The connection between their neurochemical effects and their pro-
found effects on mental function remains largely obscure.
Other substances also have psychedelic effects, but of
a qualitatively very different character from the classical
psychedelics. Among these other substances are MDMA (methylene-
dioxymethamphetamine: street name “ecstasy”), MDA (methylene-
dioxyamphetamine), salvinorin (from the plant Salvia divinorum), the
dissociative anesthetic ketamine, and anticholingeric hallucinogens
such as atropine and scopolamine. These various molecules have
distinctive neurochemical mechanisms that are quite different from
those of the classical psychedelics. As with the classical psychedelics,
the connection between their known neurochemical actions and their