How to tell if a comatose patient is actually conscious

Neurologist Steven Laureys is an expert on the mysteries of consciousness. A researcher and clinician at the Belgian National Fund of Scientific Research he's known for testing comatose patients for any hidden signs of consciousness. From Scientific American's interview with Laureys:

So how is it possible to study something as complex as consciousness?

There are a number of ways to go about it, and the technology we have at our disposal is crucial in this regard. For example, without brain scanners we would know much, much less than we now do. We study the damaged brains of people who have at least partially lost consciousness. We examine what happens during deep sleep, when people temporarily lose consciousness. We've also been working with Buddhist monks because we know that meditation can trigger alterations in the brain; connections that are important in the networks involved in consciousness show changes in activity. Hypnosis and anesthesia can also teach us a great deal about consciousness. In Lige, surgeons routinely operate on patients under hypnosis ( including Queen Fabiola of Belgium). Just as under anesthesia, the connections between certain brain areas are less active under hypnosis. And finally, we are curious to understand what near-death experiences can tell us about consciousness. What does it mean that some people feel they are leaving their bodies, whereas others suddenly feel elated?

Patients are brought to Lige from all over Europe to undergo testing. How do you determine whether they are conscious?

Well, of course, the physician will say, "Squeeze my hand"-but this time while the patient is in a brain scanner. If the motor cortex is activated, we know that the patient heard and understood and therefore is conscious. We also want to determine the chances of recovery and what the physician or the patient's family can do. With different brain scanners, I can find out where brain damage is located and which connections are still intact. This information tells family members what the chances of recovery are. If the results show that there is no hope whatsoever, we then discuss difficult topics with the family, such as end-of-life options. Occasionally we see much more brain activity than anticipated, and then we can initiate treatment aimed at rehabilitation.

"How Can We Tell If a Comatose Patient Is Conscious?" (Scientific American)

Image from the famous cover of the novel Coma by Robin Cook. More on that artwork here.