We are in the midst of what is being called the 'psychedelic renaissance' with growing interest into how psychedelics alter consciousness, brain function and brain connectivity. The acute, often profound, effects of the psychedelic experience can induce lasting improvements in mental health demonstrating that chemistry forms the basis of mystical experience, consciousness and mental wellbeing. - This volume is a collection of chapters by world leaders in fields of neurobiology, neuropsychiatry, psychology, ethnography and pharmacology, addressing the neurobiological mechanisms of action of various classic and atypical psychedelics, their therapeutic potential as well as the possible risks associated with their use