Psychedelic drugs have been used for millennia by certain cultures and are now being used by scientists and doctors in contemporary science and medicine to understand the brain and treat certain mental disorders such as depression. Dr Robin Carhart-Harris will describe his research with these unusual compounds, which includes the first ever functional brain imaging studies with LSD and psilocybin (aka 'magic mushrooms') and an ongoing study investigating whether psilocybin can be used to treat depression.