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 .
Increased frontal and paralimbic activation following ayahuasca, the pan-amazonian inebriant
Rationale Ayahuasca is a South American psychoactive plant tea which contains the serotonergic psychedelic N , N-dimethyltryptamine ( DMT ) and monoamine-oxidase inhibitors that render DMT orally active . Previous investigations with ayahuasca have highlighted a psychotropic effect profile characterized by enhanced introspective attention , with individuals reporting altered somatic perceptions and intense emotional modifications , frequently accompanied by visual imagery . Despite recent advances in the study of ayahuasca pharmacology , the neural correlates of acute ayahuasca intoxication remain largely unknown . Objectives To investigate the effects of ayahuasca administration on regional cerebral blood flow . Methods Fifteen male volunteers with prior experience in the use of psychedelics received a single oral dose of encapsulated freeze-dried ayahuasca equivalent to 1.0 mg DMT/kg body weight and a placebo in a r and omized double-blind clinical trial . Regional cerebral blood flow was measured 100–110 min after drug administration by means of single photon emission tomography ( SPECT ) . Results Ayahuasca administration led to significant activation of frontal and paralimbic brain regions . Increased blood perfusion was observed bilaterally in the anterior insula , with greater intensity in the right hemisphere , and in the anterior cingulate/frontomedial cortex of the right hemisphere , areas previously implicated in somatic awareness , subjective feeling states , and emotional arousal . Additional increases were observed in the left amygdala/parahippocampal gyrus , a structure also involved in emotional arousal . Conclusions The present results suggest that ayahuasca interacts with neural systems that are central to interoception and emotional processing and point to a modulatory role of serotonergic neurotransmission in these processes
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 .