“     During surgery, a patient awakes but is unable to move. She sees people dressed in green who talk in strange slowed-down voices. There seem to be tombstones nearby and she assumes she is at her own funeral. Slipping back into oblivion, she awakes later in her hospital bed, troubled by her frightening experiences.

These are genuine memories from a patient who regained awareness during an operation. Her experiences are clearly a distorted version of reality but crucially, none of the medical team was able to tell she was conscious.

This is because medical tests for consciousness are based on your behavior. Essentially, someone talks to you or prods you, and if you don’t respond, you’re assumed to be out cold. Consciousness, however, is not defined as a behavioral response but as a mental experience. If I were completely paralyzed, I could still be conscious and I could still experience the world, even if I was unable to communicate this to anyone else.”

continue reading | Discover Magazine

[title: W.H. Auden]

“     Hospital medicine takes a pretty crude approach to consciousness. You’re considered mentally AWOL if you don’t respond to simple commands or physical prodding. But studies of post-operative patients have found that many of them recall having dreamt during anaesthesia. And in some disturbing cases they’ve even felt pain or heard the surgeons talking. This suggests that it’s possible to be outwardly dead to the world, but conscious inside (locked-in patients and imaging studies of brain-injured patients in a persistent vegetative state also imply the same thing). Researchers have nicknamed people in this state “inverse zombies” - a play on the standard philosophical zombie concept, in which a person may appear to be outwardly conscious, but is in fact, dead inside.

A problem with much of the research into “inverse zombies” is that it’s been conducted opportunistically in hospitals. The experimental set-up is messy, the patients have a variety of health complications, and they’ve often been given a cocktail of anaesthetic drugs. These studies have found rates of awareness during anaesthesia at around 0.023 to 1 per cent and rates of anaesthesia dreaming at rates of 6 to 53 per cent.

Now Valdas Noreika and his collaborators have performed a carefully controlled lab study of subjective (or “phenomenal”) consciousness during anaesthesia, with the help of 40 healthy male university students. These brave souls were given progressively higher doses of one of four different anaesthetic drugs: dexmedetomidine; propofol (the drug that tragically killed Michael Jackson, who was using it as a sleeping aid); sevoflurane; and xenon. Dexmedetomidine and propofol are given intravenously; the other two are inhaled.”

continue reading | Research Digest | “Inverse Zombies…”

[title: Michael Jackson: Thriller][image:source]