Psychedelics afford a unique opportunity to expand our understanding of consciousness and its altered states, to develop techniques for enhancing consciousness, and to uncover new avenues of treatment and improved therapeutic techniques. In 2012, the Beckley Foundation/Imperial College Psychedelic Research Programme published the groundbreaking results from its series of studies into psilocybin using fMRI and MEG brain imaging technologies. Contrary to our expectation, we found that psilocybin decreases cerebral blood flow and brain activity, particularly in those regions that constitute the "default mode network," the network of brain regions responsible for coordinating the flow of information through the brain and filtering out what is deemed superfluous. It is by decreasing the censoring activity of this network that psilocybin produces its characteristic effects: vivid sensory awareness, unconstrained cognition, and ego-dissolution. Our work has generated valuable insights into the transition from normal awareness to the altered awareness of the psychedelic state. It has also opened up new avenues of potential treatment for depression and other conditions.