Do we live in a holographic universe? How green is your coffee? And could drinking too much water actually kill you?



Before you click those links you might consider how your knowledge-hungry brain is preparing for the answers. A new study from the University of California, Davis, suggests that when our curiosity is piqued, changes in the brain ready us to learn not only about the subject at hand, but incidental information, too.



Neuroscientist Charan Ranganath and his fellow researchers asked 19 participants to review more than 100 questions, rating each in terms of how curious they were about the answer. Next, each subject revisited 112 of the questions—half of which strongly intrigued them whereas the rest they found uninteresting—while the researchers scanned their brain activity using functional magnetic resonance imaging (fMRI).



During the scanning session participants would view a question then wait 14 seconds and view a photograph of a face totally unrelated to the trivia before seeing the answer. Afterward the researchers tested participants to see how well they could recall and retain both the trivia answers and the faces they had seen.



Ranganath and his colleagues discovered that greater interest in a question would predict not only better memory for the answer but also for the unrelated face that had preceded it. A follow-up test one day later found the same results—people could better remember a face if it had been preceded by an intriguing question. Somehow curiosity could prepare the brain for learning and long-term memory more broadly.



The findings are somewhat reminiscent of the work of U.C. Irvine neuroscientist James McGaugh, who has found that emotional arousal can bolster certain memories. But, as the researchers reveal in the October 2 Neuron, curiosity involves very different pathways.



To understand what exactly had occurred in the brain the researchers turned to their imaging data. They discovered that brain activity during the waiting period before an answer appeared could predict later memory performance. Several changes occurred during this time.



First, brain activity ramped up in two regions in the midbrain, the ventral tegmental area and nucleus accumbens. These regions transmit the molecule dopamine, which helps regulate the sensation of pleasure and reward. This suggests that before the answer had appeared the brain’s eager interest was already engaging the reward system. “This anticipation was really important,” says Ranganath’s co-author, U.C. Davis cognitive neuroscientist Matthias Gruber. The more curious a subject was, the more his or her brain engaged this anticipatory network.



In addition, the researchers found that curious minds showed increased activity in the hippocampus, which is involved in the creation of memories. In fact, the degree to which the hippocampus and reward pathways interacted could predict an individual’s ability to remember the incidentally introduced faces. The brain’s reward system seemed to prepare the hippocampus for learning.



The implications are manifold. For one, Ranganath suspects the findings could help explain memory and learning deficits in people with conditions that involve low dopamine, such as Parkinson’s disease.



Piquing curiosity could also help educators, advertisers and storytellers find ways to help students or audiences better retain messages. “This research advances our understanding of the brain structures that are involved in learning processes,” says Goldsmiths, University of London psychologist Sophie von Stumm, unconnected to the study. She hopes other researchers will replicate the work with variations that can clarify the kinds of information curious people can retain and whether results differ for subjects who have broad ‘trait’ curiosity as opposed to a temporarily induced specific interest.



Ranganath’s findings also hint at the nature of curiosity itself. Neuroscientist Marieke Jepma at the University of Colorado Boulder, who also did not participate in this study, has previously found that curiosity can be an unpleasant experience, and the brain’s reward circuitry might not kick in until there is resolution. She suspects, however, that her findings and Ranganath’s results are two sides of the same coin. To explain this, she refers to the experience of reading a detective novel. “Being uncertain about the identity of the murderer may be a pleasant reward-anticipating feeling when you know this will be revealed,” she says. “But this will turn into frustration if the last chapter is missing.”



Ranganath agrees that the hunger for knowledge is not always an agreeable experience. “It’s like an itch that you have to scratch,” he says. “It’s not really pleasant.”