Consciousness is the “hard problem” in mind science: explaining how the astonishing private world of consciousness emerges from neuronal activity. Recent research using EEG (brain-wave sensing) and fMRI (functional magnetic resonance imaging) measurements by Steven Laureys of the University of Liege offers evidence for the “global workspace theory,” and may also offer clues to the “hard problem” of how patterns of electrical activity give rise to our complex internal lives.
The global workspace model of consciousness, proposed by Bernard Baars, an Affiliated Research Fellow of The Neurosciences Institute in San Diego, California, proposes that perceptions below the threshold of consciousness are processed in relatively small, local areas of the brain. Broadcasting this pre-conscious information to the global workspace — a network of neural regions — results in conscious experience.
One way to think about Dr. Baars’ global workspace is to use a “theater” metaphor – but not the notion of a dualistic “Cartesian theater” (which assumes someone is viewing the theater) which is criticized by philosopher Daniel Dennett and others. In the theater of consciousness, a spotlight of selective attention shines a bright spot on stage. The bright spot reveals the contents of consciousness, actors moving in and out, making speeches or interacting with each other. Behind the scenes, also in the dark, are the director (executive processes), stagehands, script writers, scene designers and so forth. They shape the visible activities in the bright spot, but are themselves invisible. Baars’ theater is not located in a single place in the mind but distributed throughout it, nor is there a viewer distinct from what is being viewed.
Dr. Laureys’ recent EEG and fMRI work may be starting to probe beyond the so-called “easy” question. Laureys is board-certified in neurology and palliative and end-of-life medicine as well as invited professor at the Collège Belgique (Belgian Royal Academy of Sciences) and chair of the “European Neurological Society Subcommittee on Coma and Disorders of Consciousness.” Laureys’s team predicted that the activity of the default mode network (DMN, a region of the brain’s global workspace) should be greatest in healthy volunteers and in people with locked-in-syndrome, who may be fully conscious but can only move their eyes, while patients in a vegetative state or in a coma should have even less activity in the DMN.
To prove this theory, Laureys’ team scanned the brains of 14 people with brain damage and 14 healthy volunteers using fMRI. They showed that DMN activity dropped exponentially starting with healthy volunteers right down to those in a vegetative state. “The difference between minimally conscious and vegetative state is not easy to make on the bedside, and four times out of 10 we may get it wrong,” says Laureys. He conjectures that a person’s DMN may one day be used as a medical diagnostic procedure. “I’m predicting those with a higher level of DMN activity will be the ones who will recover from their coma, or vegetative states, or minimally conscious states,” he says.
The difference between minimally conscious and vegetative state is not easy to make on the bedside, and four times out of 10 we may get it wrong.
Philosophers David Chalmers at the Australian National University in Canberra, points out that “consciousness” is an ambiguous term since it can refer to a variety of phenomena. “Each of these phenomena needs to be explained, but some are easier to explain than others,” says Chalmers. “At the start, it is useful to divide the associated problems of consciousness into ‘hard’ and ‘easy’ problems. The easy problems of consciousness are those that seem directly susceptible to the standard methods of cognitive science, whereby a phenomenon is explained in terms of computational or neural mechanisms. The hard problems are those that seem to resist those methods.” Here’s David Chalmers on consciousness:
A recent University of California at Irvine course on consciousness examines these ideas and key players like Chalmers and Dennett in some depth. While the easy problem looks at correlations between brain activity and different states of consciousness — something that the global workspace theory is beginning to elucidate — the elusive hard problem of how these patterns of electrical activity could ever give rise to our subjectivity may never be fully solved. Dr. Laureys’ correlation of DMN activity to patients in a coma or vegetative state starts to show how the electrical patterns of the brain relate to “conscious” and “pre-conscious” states according to the global workspace theory, but doesn’t really come close to accounting for the richness of our inner lives.