LSD and other psychedelics changes the ability of the thalamus to do all this filtering (neuroscientists call it “sensory gating”), according to the theory proposed by Mark A. Geyer, Ph.D., and Franz X. Vollenweider, Ph.D., in 2008. If the thalamus can’t perform its gating duties, the brain suddenly has to deal with a lot more stimuli and goes into overdrive. We experience that flood of information as a psychedelic LSD trip (perhaps analogous to the overwhelming feeling of Twitter overload).
The new PNAS study, led by Katrin H. Preller, Ph.D., of the University Hospital for Psychiatry Zurich and co-authored by Vollenweider, dives deep into the brain to show how LSD exerts its effect on the thalamus. Since, at their peak, LSD trips have similar effects to psychiatric issues like depression and schizophrenia, understanding how the drug works could show scientists how to treat those disorders.