Science Researchers Discover Brain Activity in Vegetative Patient

A vegetative and outwardly unresponsive patient apparently was capable of understanding and responding to certain commands, as measured by a brain-imaging device, according to researchers in the 8 September 2006 issue of the journal Science.

Adrian Owen and colleagues in the United Kingdom and Belgium used fMRI brain-imaging technology to measure the neural responses of a patient who had been in a persistent vegetative state for five months since emerging from a coma. The woman had sustained severe head injuries from a traffic accident.

The patient's brain responses to spoken sentences were similar to those of healthy volunteers, while no activity was identified when exposed to non-speech sounds.

Using fMRI technology, the researchers noticed activity in the language-processing regions of her brain when words were spoken to her, specifically with sentences containing ambiguous words such as “creek/creak”.

These responses are thought to be relatively automatic and have been elicited from other vegetative subjects.

Investigating further, the authors asked the patient to imagine herself playing tennis and visiting all of the rooms in her house. Again, her brain responses closely matched those of healthy volunteers and perhaps show a deliberate effort to follow the instructions, according to the authors.

In a related Perspective, Lionel Naccache discusses whether this patient is actually conscious.

Both Naccache and Owen emphasize that it is important not to generalize from this single patient to most other vegetative-state patients. “This is unlikely the case for all vegetative patients,” Owen said. “It’s such a heterogeneous group; they all have brain injuries of different types.”

Kathy Wren

7 September 2006