LSD induces profound psychedelic effects, including changes in the meaning of percepts. The subjective effects of LSD are fully blocked by a 5-HT2A receptor antagonist. LSD may alter meaningfulness by increasing activity in cortical regions responsible for processing personal attribution.
Halberstadt, A. L. (2017). Hallucinogenic Drugs: A New Study Answers Old Questions about LSD. Current Biology, 27(4), R156-R158. 10.1016/j.cub.2016.12.058