A pharmacoimaging study examined how ayahuasca affects a brain region involved in social perception, the posterior superior temporal sulcus (pSTS), which is part of the third visual pathway. Twelve healthy volunteers received two doses of ayahuasca (0.5 mg/kg and 0.8 mg/kg DMT) or a placebo in a crossover design. The higher dose increased connectivity of the right pSTS with visual and mirror-neuron brain regions. This enhanced connectivity correlated with stronger perspective-taking experiences. Participants also reported improved social relationships one week later, even though acute effects were minimal. The findings suggest ayahuasca strengthens early social information processing through the third visual pathway and mirror-neuron systems, offering a basis for its prosocial therapeutic effects.
Thinking about the minds of others and thinking about one's own mind rely on both shared and distinct brain regions. Using fMRI and multi-voxel pattern analysis, brain activity patterns in the ventral medial prefrontal cortex encoded mental state inferences only for the self, while more dorsal regions encoded such inferences for both self and others. The posterior cingulate cortex distinguished whether the target of mental state inference was self or other. Cross-classification analysis revealed that patterns in the dorsomedial prefrontal cortex, ventromedial prefrontal cortex, and right temporoparietal junction were sensitive to mental state reasoning regardless of whether the target was self or other. These findings suggest a functional hierarchy where some brain areas support agent-specific reasoning and others support more abstract, agent-general reasoning.