Scientists find that individuals in vegetative states can learn

Scientists have found that some individuals in the vegetative and minimally conscious states, despite lacking the means of reporting awareness themselves, can learn and thereby demonstrate at least a partial consciousness. Their findings are reported in today's (20 September) online edition of Nature Neuroscience.

It is the first time that scientists have tested whether patients in vegetative and minimally conscious states can learn. By establishing that they can, it is believed that this simple test will enable practitioners to assess the patient's consciousness without the need of imaging.

This study was done as a collaborative effort between the University of Buenos Aires (Argentina), the University of Cambridge (UK) and the Institute of Cognitive Neurology (Argentina). By using classical Pavlonian conditioning, the researchers played a tone immediately prior to blowing air into a patient's eye. After some time training, the patients would start to blink when the tone played but before the air puff to the eye.

This learning requires conscious awareness of the relation between stimuli - the tone precedes and predicts the puff of air to the eye. This type of learning was not seen in the control subjects, volunteers who had been under anaesthesia.

The researchers believe that the fact that these patients can learn associations shows that they can form memories and that they may benefit from rehabilitation.

Lead author Dr Tristan Bekinschtein, from the University of Cambridge's Wolfson Brain Imaging Unit, said: "This test will hopefully become a useful, simple tool to test for consciousness without the need for imaging or instructions. Additionally, this research suggests that if the patient shows learning, then they are likely to recover to some degree."

In 2006, the Cambridge Impaired Consciousness Group at the Wolfson Brain Imaging Unit showed, using functional imaging, showed that patients in vegetative states (as defined by behavioural assessment in the clinic) can in fact be conscious despite being unable to show consistent voluntary movements.

More information: The paper 'Classical conditioning in the vegetative and minimally conscious state' will be published in the Advanced Online Publication of Nature Neuroscience on 20 September 2009.

Source: University of Cambridge (news : web)

   

• RobertKarlStonjek - Sep 20, 2009
  • Rank: 4.2 / 5 (5)
  Consciousness is not required for learning to occur in normals.
  Conscious awareness IS NOT required for the eye-puff response. Consciousness is far to slow for such a response (requires >500ms for a response). Further, associations can occur entirely outside consciousness, as has been demonstrated ad-nauseam in numerous psychological studies.
  
  Try NOT responding to the eye blink-tone association. If it was a consciously mediated response then you'd have no problem doing this, but in fact it is quite difficult to achieve.
  
  Robert Karl Stonjek
  • report abuse
  • • Current rank
    • 1
    • 2
    • 3
    • 4
    • 5
• docknowledge - Sep 20, 2009
  • Rank: not rated yet
  That being said, RobertKarl, it would certainly be handy if comatose patients could learn at least a small number of things -- in case they revive.
  
  Knowing the names of children who have been born in the family, or that people have died. Even things such as what's going on with their favorite singers or movie stars might make the shock coming back less severe?
  • report abuse
  • • Current rank
    • 1
    • 2
    • 3
    • 4
    • 5
• Myria83 - Sep 21, 2009
  • Rank: not rated yet
  Another ground to compete over as an argument against euthanasia...? I hope this study's result won't be strumentalized.
  • report abuse
  • • Current rank
    • 1
    • 2
    • 3
    • 4
    • 5