Primates are notorious for their curiosity and they seek out novelty, even if it doesn’t come with an immediate reward. While this trait is a key feature of humans and nonhuman primates alike, the brain circuitry that regulates novelty seeking has been a matter of speculation. In a study published in Nature Neuroscience December 13, Ilya Monosov, PhD, associate professor in the Department of Neuroscience at Washington University School of Medicine, with postdoctoral fellow Dr. Takaya Ogasawara and colleagues in the Monosov lab, show that the zona incerta—a region deep within the brain—is responsible for controlling novelty seeking in animals.
“It has all the key signals to control novelty-driven motivation,” says Monosov. “For example, zona incerta neurons predict future novel objects and move our gaze to them. Turning them off, disrupts novelty seeking”
An important insight from the discovery is also that the mechanism for novelty-seeking can be separate from the reward system—in other words, there is a brain circuit for seeking out novelty for novelty’s sake.
In their study, the authors first set out to test the idea that novelty seeking might be encoded by the reward system. They first showed that animals predict and actively seek out novelty similarly to how they seek out primary rewards. They then sought to test if dopamine-producing neurons, known to regulate reward seeking, could also regulate novelty seeking. Surprisingly, the researchers found that dopamine neurons were indifferent to predictions of future novelty.
Next, the research team turned to the adjacent zona incerta (ZI). “The ZI is ideally suited to control novelty seeking behavior,” Monosov explains. The ZI receives input from higher-order visual areas that encode meaning and novelty of objects, and projects to the superior colliculus, which controls the eye. When animals performed novelty seeking, ZI neurons there were active. And when ZI cells’ activity was disrupted, the animals had less motivation to look for novel images.
The finding dissociates the mechanisms of reward-seeking and novelty-seeking when novelty has on extrinsic reward value, illustrating that the motivation to experience novelty can be independent from the motivation to gain reward.
Monosov says one of the interesting aspects of the zona incerta is that it appears to be a relay station for novelty seeking—processing information about the novelty and directly sending that signal to the motor control area that regulates gaze shifts—without additional stops along the way.