10/10/2014 08:20 am ET Updated Dec 06, 2017

For Memory, Curiosity Is Its Own Reward

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By Nathan Collins

Perhaps curiosity is its own reward. It's a lot easier to learn something when you're interested in it, and there's certainly something inherently motivating about being curious. Now, a team of researchers think they know why: The same brain circuits seem to control both curiosity and our responses to money, tasty food, and other sorts of external motivation.

Neuroscientists Matthias Gruber, Bernard Gelman, and Charan Ranganath developed that hypothesis after contemplating a 2009 study that connected curiosity to the caudate nucleus, a brain region that neuroeconomists believe plays a role in learning and processing rewards (among many other things). To Gruber's team, there remained unanswered questions. How was curiosity related to motivation? Why does curiosity aid learning? And could curiosity about one topic help someone learn about another?

To answer those questions, the trio posed a series of trivia questions to experimental participants who, after viewing each, rated both how likely they were to know the answer and how curious they were to learn that answer. The team didn't, however, reveal those answers right away. Instead, in the second phase of the experiment, they had each of their subjects hop into an fMRI brain scanner, where they once again saw each trivia question, followed by a picture of a face four seconds later, and the question's answer six seconds after that. Unbeknownst to participants at the time, they were about to be tested on both the faces and the trivia answers. In the meantime, the researchers trained their attention on three brain regions of interest: the substania nigra/ventral tegmental complex, or SN/VTA, the hippocampus, and the nucleus accumbens. Those three, previous studies suggest, work together to assist memory formation, especially when we're expecting a coming reward.

The results? When participants were more curious to know a question's answer, there was more activity in both the nucleus accumbens and SN/VTA. And the more curious someone was, the more activity there was. The hippocampus seemed to respond most when an individual was both curious about an answer and remembered that answer in the post-scanner test. That, the researchers argue, means there's a neural connection between curiosity, motivation, and memory: the curiosity and memory elements were actually observed, and previous studies had indicated the involvement of all three brain regions in motivation.

The team next looked at what participants had actually learned. Participants, they found, correctly recalled 70.6 percent of the answers they were more curious about, compared with 54.1 percent of those they found less interesting. What's more, curiosity about the trivia had a smaller but noticeable effect on memory for the faces, too. When their curiosity was piqued, experimental subjects recognized 42.4 percent of the faces they saw, compared with 38.2 percent when they were less curious.

Writing Monday in the journal Neuron, the authors suggest their study may have implications for learning and memory in seniors or patients with psychiatric disorders that affect the brain's motivational circuits. Stimulating curiosity, they argue, may be one way to help patients learn and hold on to new memories.



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