“For the past twelve years”, says [Stanislas] Dehaene, “my research team has been using every available brain research tool, from functional MRI to electro- and magneto-encephalography and even electrodes inserted deep in the human brain, to shed light on the brain mechanisms of consciousness. I am now happy to report that we have acquired a good working hypothesis. In experiment after experiment, we have seen the same signatures of consciousness: physiological markers that all, simultaneously, show a massive change when a person reports becoming aware of a piece of information (say a word, a digit or a sound).
“Furthermore, when we render the same information non-conscious or “subliminal”, all the signatures disappear. We have a theory about why these signatures occur, called the global neuronal workspace theory. Realistic computer simulations of neurons reproduce our main experimental findings: when the information processed exceeds a threshold for large-scale communication across many brain areas, the network ignites into a large-scale synchronous state, and all our signatures suddenly appear.
“But this is already more than a theory. We are now applying our ideas to non-communicating patients in coma, vegetative state, or locked-in syndromes. The test that we have designed with Tristan Bekinschtein, Lionel Naccache, and Laurent Cohen, based on our past experiments and theory, seems to reliably sort out which patients retain some residual conscious life and which do not…”