Consciousness in the vegetative state

David Metz | 8th November 2017 | Feature post

A most interesting new book by Adrian Owen, a neuroscientist, entitled ‘Into the Gray Zone’, explores what he terms the border between life and death. The author has used brain imaging techniques to understand what brain function exists for people who are in a vegetative state as a result of brain injury. They display no evidence of consciousness, not responding to external stimulation. However, he has discovered that 15 to 20 per cent of people in the vegetative state are fully conscious although unable to communicate.

Brain scans can detect which parts of our brains function when we carry out particular tasks. For this purpose, healthy volunteers participate in scanning tests. If they are asked to imagine, for example, that they are playing tennis, they all show activity in the same area of the brain. If they are asked to imagine they are walking through their home, another part of the brain is active.

Some patients in the vegetative state respond in the same way when asked to imagine these behaviours, while located in the brain scanner. The two imagined responses can be used to ask yes/no questions: imagine your are playing tennis if the answer to a question is ‘yes’, walking through your home if ‘no’. This allows the state of mind of such brain-injured patients to be explored, as recounted by the author in a number of moving case studies

The book also reports a study of 91 patients with locked-in syndrome – conscious people who were only able to communicate by blinking or moving their eyes. 72 per cent reported that they were happy, contrary to what most of us might expect, and to what we might have assumed when preparing our Advance Decisions.





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