Humans have the ability to learn and interact with the world being aware of their own experience. This knowledge about one´s awareness is called “metacognition” and it is one of the major characteristics that differentiate humans from other species. But, what are the brain mechanisms underlying consciousness? How does the brain create different consciousness states? Modern Neuroscience has investigated these questions for centuries, but yet we have no idea how consciousness arises in the brain. Although brain technology has hugely progressed in the last decades, for researchers is very difficult to study conscious experiences because they are entirely subjective and cannot be accessed by others. Thus, measuring consciousness in experimental conditions it is almost impracticable without getting contaminated by subjective biases.