During the teen years, the human brain responds more to rewards than in adulthood. This is not usually considered a good thing, as it is linked with impulsivity and risk taking.
But this sensitivity has an upside too, Daphna Shohamy, a cognitive neuroscientist at Columbia University’s Zuckerman Institute, is finding. “We thought there’s likely to be more to the story,” she says.
In a recent experiment, teens did better than adults on a computer game __that allowed them to learn from correct guesses. Two brain areas seem to work together to help teens succeed at this kind of learning and perhaps prepare for adulthood, Shohamy and her colleagues reported today in the journal Neuron.
“If a developing brain opens up a vulnerability to one thing, we have to think about the flip side and see well…is it adaptive another way?" says Heather Brenhouse, a developmental neuroscientist and professor of psychology at Northeastern University in Boston, who was not involved in the research. "And this is great evidence for that.”
Shohamy and her colleagues invited 41 teens between the ages of 13 and 17, and 31 adults aged 20 to 30, to play a computer game. The goal was to figure out which of two flowers different butterflies would alight upon. Each butterfly had a flower __that it sometimes (but not always) preferred. Each time the players guessed which flower a bug would choose, they were told whether they were right or wrong and shown an image of an unrelated object like a birdhouse.
Teens were better than adults at discerning which plant a butterfly favored over time--and how well they performed on the game correlated with how many of the random objects they later recalled. “We didn’t find they were overall better at memory, but what they remembered was related to how they were learning,” Shohamy says.
For adults, having a good memory of this context didn’t seem connected to their performance. The teens “were bringing these two ways of learning together at the same time and in cooperation,” Shohamy says. “Whereas in the adults, it was like these two things were happening in parallel but not really communicating.”
She and her team also imaged the players’ brains with a fMRI. The hippocampus--an area important for memory--became more active during gameplay in the teenaged brains. And this region also seemed to be working in tandem with a reward-related area called the striatum. This indicates that these regions play slightly different roles in adolescence than in later years.
Perhaps, Shohamy says, similar brain mechanisms might underlie both risk taking and learning. “In our daily lives, we’re constantly producing actions and receiving feedback on those actions and updating our expectations for next time,” she says. Having this kind of learning amped up may prepare teenagers to become independent.
“That’s what this mechanism in the brain is giving them, it’s sort of this better learning…about the environment they’re in when they’re on the verge of adulthood,” Shohamy says.