cally identified.
Perhaps the most famous psychedelic chemical is LSD. Its profound
psychoactive properties were not known until it was synthesized and
tested in 1943 by Albert Hofmann (1906-2008). It is derived from er-
gotamine, produced by a fungus called Claviceps purpurea, also known
as ergot. LSD is one of the most potent psychoactive substances
known, active in quantities of a few micrograms.
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LSD ErgotamineAlbert Hofmann’s discovery of LSD’s potent and complex effects on
the mind was a landmark event in the history of neuroscience. Before
the 1940s, the workings of the brain were not conceptualized as being
closely associated with chemical signaling. Only a single molecule,
acetylcholine, was known to be a neurotransmitter, and this was asso-
ciated with the peripheral nervous system, not the CNS. The discovery
that a few millionths of a gram of a chemical could have profound
effects on thinking, feeling, perception, and conscious awareness
really made the point that there were powerful chemical connections
between brain physiology and mental experience. This may seem
obvious now—just like genes being made of DNA might seem obvious