A 25-year science wager has come to an end. In 1998, neuroscientist Christof Koch bet philosopher David Chalmers that the mechanism by which the brain’s neurons produce consciousness would be discovered by 2023. Both scientists agreed publicly on 23 June, at the annual meeting of the Association for the Scientific Study of Consciousness (ASSC) in New York City, that it is an ongoing quest — and declared Chalmers the winner.

What ultimately helped to settle the bet was a study testing two leading hypotheses about the neural basis of consciousness, whose findings were unveiled at the conference.

“It was always a relatively good bet for me and a bold bet for Christof,” says Chalmers, who is now co-director of the Center for Mind, Brain and Consciousness at New York University. But he also says this isn’t the end of the story, and that an answer will come eventually: “There’s been a lot of progress in the field.”

The great wager

Consciousness is everything that a person experiences — what they taste, hear, feel and more. It is what gives meaning and value to our lives, Chalmers says.

Can lab-grown brains become conscious?

Despite a vast effort, researchers still don’t understand how our brains produce it, however. “It started off as a very big philosophical mystery,” Chalmers adds. “But over the years, it’s gradually been transmuting into, if not a ‘scientific’ mystery, at least one that we can get a partial grip on scientifically.”

Koch, who holds the title of meritorious investigator at the Allen Institute for Brain Science in Seattle, Washington, began his search for the neural footprints of consciousness in the 1980s. Since then, he has been invested in identifying “the bits and pieces of the brain that are really essential — really necessary to ultimately generate a feeling of seeing or hearing or wanting”, as he puts it.

At the time Koch proposed the bet, certain technological advancements made him optimistic about solving the mystery sooner rather than later. Functional magnetic resonance imaging (fMRI), which measures small changes in blood flow that occur with brain activity, was taking laboratories by storm. And optogenetics — which allowed scientists to stimulate specific sets of neurons in the brains of animals such as nonhuman primates — had come on the scene. Koch was a young assistant professor at the California Institute of Technology in Pasadena at the time. “I was very taken by all these techniques,” he says. “I thought: 25 years from now? No problem.”

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