LSD Increases Primary Process Thinking via Serotonin 2A Receptor Activation Rainer Kraehenmann, Dan Pokorny, Helena Aicher, Katrin H. Preller, Thomas Pokorny, Oliver G. Bosch, Erich Seifritz and Franz X. Vollenweider Frontiers in Pharmacology, 2017, Volume 8, Article 814, 1-9. Doi : 10.3389/fphar.2017.00814   Rationale : Stimulation of serotonin 2A (5-HT2A) receptors by lysergic acid diethylamide (LSD) and related compounds such as psilocybin has previously been shown to increase primary process thinking – an ontologically and evolutionary early, implicit, associative, and automatic mode of thinking which is typically occurring during altered states of consciousness such as dreaming. However, it is still largely unknown whether LSD induces [...]