
© iStockphoto/SebchandlerLATENT LEARNING?: If some vegetative patients can be shown to acquire conditional learning, should their status be reevaluated?
Brain-damaged patients who appear to have lost signs of conscious awareness might still be able to create new memories, showing signs of new neural networks and potential for partial recovery.In patients who have survived severe brain damage, judging the level of actual awareness has proved a difficult process. And the prognosis can sometimes mean the difference between life and death.
New research suggests that
some vegetative patients are capable of simple learning - a sign of consciousness in many who had failed other traditional cognitive tests. The findings are presented in a paper today in
Nature Neuroscience.
To decide whether patients are in a minimally conscious state (MCS), in which there is some evidence of perception, or intentional movement or have sunk into a vegetative state (VS), where there is neither, doctors have traditionally used a battery of tests and observations, many of which require some subjective interpretation, such as deciding whether a patient's movements are purposeful - to indicate a sullied feeding tube, for example - or just random.