Scientists One Step Closer to Defining Consciousness

Using brain imaging techniques to observe the brain as it slips into unconsciousness, researchers say they have taken a significant step toward establishing a scientific definition of consciousness.

"In terms of brain function, the difference between being conscious and unconscious is a bit like the difference between driving from Los Angeles to New York in a straight line versus having to cover the same route hopping on and off several buses that force you to take a 'zig-zag' route and stop in several places," lead study author Martin Monti, an assistant professor of psychology and neurosurgery at the University of California, Los Angeles, said in a statement.

"It turns out that when we lose consciousness, the communication among areas of the brain becomes extremely inefficient," he explained, "as if suddenly each area of the brain became very distant from every other, making it difficult for information to travel from one place to another."

The scientists used functional magnetic resonance imaging (fMRI) to reveal how this information moved in the brains of 12 volunteers -- six men and six women -- as they became unconscious after being treated with propofol.

The researchers then used a branch of mathematics known as graph theory to analyze the "network properties" of the participants' brains. Graph theory is used to study, among other things, air-traffic patterns and information on the Internet.

The findings suggest that consciousness does not occupy one particular place in the brain. Instead, it "arises from the mode in which billions of neurons communicate with one another," the psychologist said.

In fact, Monti hypothesizes that patients who enter a coma due to severe brain damage likely impaired their brain function in a manner similar to the effects of anesthesia.

"If this were indeed the case, we could imagine in the future using our technique to monitor whether interventions are helping patients recover consciousness," he said.