Inhaled salvinorin A, the active ingredient in Salvia divinorum, produces transient psychotomimetic and perceptual alterations including dissociative and somaesthetic effects, increases plasma cortisol and prolactin, and reduces resting electroencephalogram spectral power. It does not cause euphoria, cognitive deficits, or changes in vital signs, and the effects are not dose-related. The substance is very well-tolerated without acute or delayed adverse effects, and its lack of euphoric effects suggests a low addictive potential similar to other hallucinogens.
The balance between excitatory and inhibitory (E/I) activity in the brain is important for normal function, and its disruption is linked to psychiatric disorders. In a randomized, double-blind, placebo-controlled study, healthy volunteers received low doses of ketamine (which shifts E/I balance toward excitation) and thiopental (which shifts it toward inhibition) while their brain activity was recorded with EEG. The drugs altered the aperiodic exponent of the power spectrum in opposite directions, matching computational predictions. Changes in the exponent correlated with subjective and cognitive effects, suggesting that this measure could serve as a noninvasive EEG biomarker for transient shifts in cortical E/I balance.