Two primary compounds, ibotenic acid and muscimol, are known to occur in pharmacologically active levels and are partially, if not entirely, responsible for Amanita muscaria's psychoactive effects.
Ibotenic acid is the most abundant of the principal compounds, and easily degrades into muscimol through the loss of a carboxyl group.
The psychoactivity of ibotenic acid has been pegged at 1 mg/kg (Ott 1993), making Waser's dose a very light one.
There is some uncertainty as to whether muscimol occurs in fresh specimens of Amanita muscaria, or whether it only appears once drying and decarboxylation of ibotenic acid commences (Catalfomo & Eugster 1970).
Unlike ibotenic acid, only trace amounts of muscimol pass through the urine unmetabolized (Ott 1993).
When the monkeys had developed a severe and stable form of the disease, the team injected a neurotoxin called ibotenic acid directly into the subthalamic nucleus of each animal's brain.
The ibotenic acid destroyed some neurons in that region of the monkey brains, slowing the neuron-firing rate, he speculates.