The dopamine signal can make novelty seem attractive, but the drive to exploit known rewards is still powerful. Other pathways are needed to fully engage exploratory behavior. In the brainstem, close to where dopamine neurons originate, a set of blue-tinted neurons form the locus coeruleus. Instead of dopamine, neurons in this place use noradrenalin to control activity in other neurons. Compared with the dopamine system, this tiny region sends projections to almost every part of the brain. So activation of these noradrenaline neurons can cause major changes in all aspects of brain function.
In turn, the frontal cortex constantly updates the noradrenaline system with information about the status of your current tasks and reward predictions. Imaging the brain at the moment where people choose to switch from exploiting known rewards to exploring unknown choices, you can see these regions of the frontal cortex get activated.
Armed with a powerful grip over behavior, the activity in this noradrenaline pathway can determine whether we should stay focused on our current mission, or if it’s time to venture out and explore the unknown.