APA Dictionary of Psychology

the highly poisonous mushroom Amanita muscaria, so called because it was once used as an insecticide to kill flies. Muscarine was the first active ingredient to be identified, but it is now known that ibotenic acid and its metabolite muscimol, which is similar in structure to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and acts as a GABA agonist, are the principal active components. Effects on humans are initially stimulating, ranging from euphoria through hallucinations to hyperactivity or excitement, and then sedating, inducing deep sleep. Symptoms of poisoning include dizziness, abdominal pains, vomiting, muscle cramps, and movement difficulties; at higher doses, these symptoms may be followed by unconsciousness, asphyxiation, coma, and potentially death. Fly agaric has been variously identified as the substance taken by Norse berserkers before battle, as the plant soma worshipped in ancient times, and, in fiction, as the mushroom eaten by Alice before she perceived objects larger than life in Lewis Carroll’s Alice in Wonderland.