A team led by neuropsychologist Dr Adrian Owen has reported on a patient who supposedly fulfilled all the criteria for a diagnosis of persistent vegetative state (PVS) but was found to have conscious awareness.
This seems a little confusing to me, as PVS is usually defined as where ‘higher’ cognitive abilities, such as awareness, are not present.
Unfortunately, I can’t read the article in full as I’m still away from home, but I suspect the diagnosis is usually based on observations of external signs of awareness, whereas Owen’s group used fMRI (a type of ‘brain scanning’) to look for changes in brain activation that would not necessarilly result in observable behaviour.
There’s a good write-up over at the BBC site with accompanying video, and for those with access to the full-text of the journal Science the original paper is available online.
This is similar to a recent study (covered previously on Mind Hacks) where researchers found evidence for similar sorts of ‘higher’ cognitive function in two patients in a ‘minimally conscious state‘.
It is likely, however, that all of these patients have suffered some problems with mental function, owing to extensive brain injury.
As psychology and neuroscience are able to measure brain function in more direct ways, rather than solely through observable behaviour, these sorts of coma-like states are likely to be found to be much more complex than previously thought.
However, neither of these conditions should be confused with ‘locked-in syndrome‘, where the cortex of the brain is largely undamaged, but selective damage to the brain stem means that the person cannot move his or her body and is often totally paralysed, despite being mentally intact.
One of the most powerful books I have ever read is the The Diving Bell and the Butterfly, written by the ex-editor of Elle magazine, who suffered a stroke and became ‘locked in’.
He wrote the book by indicating single letters with his only form of movement – an eye blink. The book is a transcendent description of his experience both before and after the onset of his condition.
Bauby died two days after the book was published but left the world with one of its most beautiful and unique literary works.