Will we ever be able to locate consciousness within the brain? It is a question that, a quarter of a century ago, two researchers aimed to settle with a wager that is due to expire in 2023.
In 1998, , now at the Allen Institute for Brain Science in Seattle, bet , now at New York University, that scientists would discover a specific signature – or neural correlate – of consciousness within 25 years.
“I was a young academic, I was at the world’s best research university,” says Koch. “I was inexperienced, I thought ‘OK, we’re going to nail this problem’.” Now, he admits he has probably lost. “I’ll bring David a good bottle of red wine,” he says.
Advertisement
The bet’s end will be marked at the in June 2023. Chalmers is coy when asked if he is confident in winning. “Miracles could happen in six months,” he says.
Finding the neural correlates of consciousness could have medical applications, such as determining if someone in a coma is self-aware, and could also help illuminate deep philosophical questions. “Consciousness comes prior to physics, comes prior to science – the only way I experience the world is through consciousness,” says Koch.
“If we understand consciousness, we’ll understand ourselves a whole lot better,” says Chalmers.
They are part of a team hoping to test two major theories of consciousness that developed in the years after their bet.
The first idea, called global workspace theory, suggests that the brain only produces a signal when you first become consciously aware of an object, and then the signal disappears. Under this theory, the brain processes non-conscious experiences in sensory areas, such as the visual cortex, and we only become aware of them if this information is then broadcast to a cluster of neurons distributed across the brain that integrate multiple senses into a single flash of perception. Brain regions that have dense links to others, such as the prefrontal or parietal areas, are prime candidates for these neurons, says Koch.
The other idea, integrated information theory, argues that if you are aware of an object for a period of time, there must be a signal of consciousness for the same duration. The theory suggests that this signal will be discovered in the posterior cortex, as researchers have previously found that some neurons in this region are particularly active when measuring conscious perception.
One experiment the team is planning will involve participants playing a video game while having their brains scanned. The game will include random objects that may or may not be perceived by the player. Afterwards, the participants will report which of these stimuli they perceived, in the hope of identifying which parts of the brain are linked with conscious perception. If signals in these areas come and go, that would favour global workspace theory, while persistent signals would point at integrated information theory.
The results of the study will be published in 2023, but are unlikely to be the final word on the difficult problem of consciousness, says Koch. “The brain is by far the most complex piece of active matter in the known universe.”
