An attempt to explain how the brain remains focused on long-term goals was made by researchers.
A new study from MIT suggests how the brain achieves this task, and indicates that the neurotransmitter dopamine may signal the value of long-term rewards.
The findings may also explain why patients with Parkinson's disease - in which dopamine signaling is impaired - often have difficulty in sustaining motivation to finish tasks.
Previous studies have linked dopamine to rewards, and have shown that dopamine neurons show brief bursts of activity when animals receive an unexpected reward.
These dopamine signals are believed to be important for reinforcement learning, the process by which an animal learns to perform actions that lead to reward.
In most studies, that reward has been delivered within a few seconds. In real life, though, gratification is not always immediate.
Animals must often travel in search of food, and must maintain motivation for a distant goal while also responding to more immediate cues.
The same is true for humans: A driver on a long road trip must remain focused on reaching a final destination while also reacting to traffic, stopping for snacks, and entertaining children in the back seat.
The study is published in the journal Nature.