Sometimes the hardest part of doing an unpleasant task is simply getting started — typing the first word of a long report, lifting a dirty dish on the top of an overfilled sink or removing clothes from an unused exercise machine. The obstacle isn't necessarily a lack of interest in completing a task, but the brain's resistance to taking the first step.
Now, scientists might have identified the neural circuit behind this resistance, and a way to ease it. In a study1 published in Current Biology, researchers describe a pathway in the brain that seems to act as a 'motivation brake', dampening the drive to begin a task. When the team selectively suppressed this circuit in macaque monkeys, goal-directed behaviour rebounded.
Motivated macaques
Previous work on task initiation has implicated a neural circuit connecting two parts of the brain known as the ventral striatum and ventral pallidum, both of which are involved in processing motivation and reward. But attempts to isolate the circuit's role have fallen short.
In the new study, Amemori and his team used a more precise approach. They first trained two male macaque monkeys (Macaca fuscata) to perform two decision-making tasks. In one, completion earned them a water reward; in the other, the reward was paired with an unpleasant puff of air to the face. Each trial required the monkeys to initiate the task by fixing their gaze on a central spot on a screen until the reward – punishment offer appeared. This allowed the researchers to measure motivation by how often the monkeys failed to begin.
Not surprisingly, the monkeys were more hesitant to begin when the possibility of punishment loomed. But that changed when the team used a targeted genetic technique to suppress signalling from the ventral striatum to the ventral pallidum. Although the suppression had little effect on the monkeys' behaviour during the reward-only trials, it made them significantly more willing to start in the face of a potentially unpleasant outcome. The suppression did not, however, alter how the animals weighed reward against punishment.
The team had effectively disabled the motivation brake. The study's behavioural data and electrophysiological recordings suggest that the ventral striatum detects aversive conditions and suppresses ventral pallidum activity, which made the animals less likely to act. "The ventral pallidum could be the centre for motivation deficit or apathy in depression," says Amemori.
If confirmed in humans, the findings could shift how clinicians approach one of depression's most debilitating symptoms. Current treatments often aim to restore enjoyment or reduce anxiety, yet many individuals continue to struggle to start simple tasks. By pinpointing a circuit that selectively dampens motivation in the face of discomfort, the study opens the door to therapies that could focus on lowering that barrier.