Long-term use was associated with thinning of the posterior cingulate cortex , thickening of the anterior cingulate cortex , and decreased neocortical 5-HT2A receptor binding .
Despite the high method ological heterogeneity and the small sample sizes , the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex
Serotonergic hallucinogens produce alterations of perceptions , mood , and cognition , and have anxiolytic , antidepressant , and antiaddictive properties .
These drugs act as agonists of frontocortical 5-HT2A receptors , but the neural basis of their effects are not well understood .
Thus , we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man .
5-HT Modulation of Dopamine Release in Basal Ganglia in Psilocybin-Induced Psychosis in Man—A PET Study with [11C]raclopride
The modulating effects of serotonin on dopamine neurotransmission are not well understood , particularly in acute psychotic states .  Positron emission tomography was used to examine the effect of psilocybin on the in vivo binding of [11C]raclopride to D2-dopamine receptors in the striatum in healthy volunteers after placebo  and a  psychotomimetic dose of psilocybin ( n = 7 ) .  Psilocybin is a potent indoleamine hallucinogen and a mixed 5-HT2A and 5-HT1A receptor agonist . Psilocybin administration ( 0.25 mg/kg p.o . ) produced changes in mood , disturbances in thinking , illusions , elementary and complex visual hallucinations and impaired ego-functioning .  Psilocybin significantly decreased [11C]raclopride receptor binding potential ( BP ) bilaterally in the cau date nucleus ( 19 % ) and putamen ( 20 % ) consistent with an increase in endogenous dopamine . Changes in [11C]raclopride BP in the ventral striatum correlated with depersonalization associated with euphoria . Together with previous reports of 5-HT receptor involvement in striatal dopamine release , it is concluded that stimulation of both 5-HT2A and 5-HT1A receptors may be important for the modulation of striatal dopamine release in acute psychoses . The present results indirectly support the hypothesis of a serotonin-dopamine dysbalance in schizophrenia and suggest that psilocybin is a valuable tool in the analysis of serotonin-dopamine interactions in acute psychotic states
Long-term use was associated with thinning of the posterior cingulate cortex , thickening of the anterior cingulate cortex , and decreased neocortical 5-HT2A receptor binding .
Despite the high method ological heterogeneity and the small sample sizes , the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex
Serotonergic hallucinogens produce alterations of perceptions , mood , and cognition , and have anxiolytic , antidepressant , and antiaddictive properties .
These drugs act as agonists of frontocortical 5-HT2A receptors , but the neural basis of their effects are not well understood .
Thus , we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man .