Scientists find that individuals in vegetative states can learn

Sep 20, 2009

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 .

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 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 on 20 September 2009.

Source: University of Cambridge (news : web)

Explore further: How nerve cells communicate with each other over long distances

add to favorites email to friend print save as pdf

Related Stories

Misdiagnosis of disorders of consciousness still commonplace

Jul 21, 2009

A sixteen-month study of consensus-based diagnosis of patients with disorders of consciousness has shown that 41% of cases of minimally conscious state (MCS) were misdiagnosed as vegetative state (VS), a condition associated ...

Brain energy use key to understanding consciousness

Jun 16, 2009

High levels of brain energy are required to maintain consciousness, a finding which suggests a new way to understand the properties of this still mysterious state of being, Yale University researchers report.

Subliminal learning demonstrated in the human brain

Aug 27, 2008

Although the idea that instrumental learning can occur subconsciously has been around for nearly a century, it had not been unequivocally demonstrated. Now, a new study published by Cell Press in the August 28 issue of the ...

Scientists Explore Consciousness

Feb 18, 2008

An international team of scientists led by a University of Leicester researcher has carried out a scientific study into the realm of consciousness. The scientists have made a significant step into the understanding of conscious ...

Conscious, unconscious memory found linked

Apr 04, 2006

Yale University scientists say they have found the way our brain stores new, conscious information is linked with the way it stores unconscious information.

Recommended for you

Why your favourite song takes you down memory lane

Aug 28, 2014

Music triggers different functions of the brain, which helps explain why listening to a song you like might be enjoyable but a favourite song may plunge you into nostalgia, scientists said on Thursday.

Transcranial Magnetic Stimulation of brain boosts memory

Aug 28, 2014

Stimulating a particular region in the brain via non-invasive delivery of electrical current using magnetic pulses, called Transcranial Magnetic Stimulation, improves memory, reports a new Northwestern Medicine ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

NeilFarbstein
Sep 20, 2009
This comment has been removed by a moderator.
RobertKarlStonjek
4.2 / 5 (5) Sep 20, 2009
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
docknowledge
not rated yet Sep 20, 2009
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?
Myria83
not rated yet Sep 21, 2009
Another ground to compete over as an argument against euthanasia...? I hope this study's result won't be strumentalized.