As artificial intelligence systems become more sophisticated, we’ve grown accustomed to hearing about how they take over human domains. AI can now beat humans at Go, write clickbait and screenplays, pick out targets in drone image data, and drive our cars.

Most of these AI systems are neural networks, a type of computing architecture loosely modeled after the human brain. For now, each of these neural nets are compartmentalized and optimized for one particular task—the AI that can beat us at Go doesn’t know how to drive a car.

The hope is that one day, however, these “narrow” AI systems will coalesce into an artificial general intelligence (AGI), or a computer that is able to a wide variety of tasks as well or better than a human. Mainen is a researcher at the Champalimaud Center for the Unknown in Portugal and spends a lot of time thinking about depression.

Depression is a relatively common phenomenon that afflicts over 300 million people worldwide and is closely linked with the neurotransmitter serotonin. As Mainen noted during a presentation last month at the Canonical Computations in Brains and Machines conference in New York, serotonin is a neuromodulator, a specific kind of neurotransmitter used to send messages across large areas of the brain.

According to Mainen, research on serotonin has shown that it plays a large role in the brain’s ability to adapt to unfamiliar situations. “People think of serotonin as related to happiness, but serotonin neurons appear to send a message that is not good or bad, but more ‘oops’ or surprise,” Mainen told Science after his presentation. Read more from…

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