London, June 14 : A new study suggests that a "default network" in the brain's cortex, which is believed to be associated with daydreaming, may provide clues as to whether severely brain-damaged patients may regain consciousness.
Dr. Steven Laureys of the University of Liege in Belgium says that this default network can stay active even in severely brain-damaged patients.
While making a presentation during a conference, he said that the network appeared to match the level of consciousness of the patient.
The researcher said that the default network seemed to be more active when the brain was not actively working on a goal, and thus the proposed link with daydreaming.
Dr. Laureys said that activity within the network might help confirm the level of consciousness of a patient, and thereby enable doctors to decide whether or not to treat him/her.
For his study, the researchers measured activity in the 13 brain-injured patients, who had a variety of different levels of consciousness.
While some of the patients were "minimally conscious", others were in a coma or a persistent vegetative state (PVS). A final group were "brain dead".
It was observed that normal activity in the area had fallen by about 10 per cent in minimally conscious patients, while it had fallen by approximately 35 per cent in coma and PVS patients.
The brain-dead patients did not show any activity at all, said Dr. Laurey.
He believes that this could be more reliable method of assessing patients.
"We could just scan someone for 10 minutes and get an easily quantifiable readout," New Scientist magazine quoted him as saying.
Cambridge University neuroscientist Jon Simons hailed the study as "very interesting".
"It suggests that connectivity in the default network might correlate with level of consciousness as measured by a coma-recovery scale," he said.
"Although the functional significance of the default network is still being hotly debated, this study does suggest that scans of the default network might perhaps have clinical utility as a diagnostic tool," he added.