In the years when psychedelic science had been shut down, Amanda Feilding helped jump-start research into altered states of mind. Today, she's in her 80s and remains active in psychedelic research with her Beckley Foundation.

Neuroscientist Christof Koch has pioneered the scientific investigation of consciousness. Recently, he had a mind-blowing experience — both terrifying and ecstatic — with 5-MeO-DMT,  also known as toad venom.