AsianScientist (Apr. 07, 2026)– We all know the feeling: a task clearly worth doing, yet something holds us back. For most, it’s temporary procrastination. But for those with major depressive disorder (MDD) or schizophrenia, this paralysis runs deeper—a condition called avolition, where even simple actions feel impossible. The neural mechanisms behind this collapse of motivation have remained poorly understood.
In a study published in Current Biology, researchers at Kyoto University’s Institute for the Advanced Study of Human Biology (WPI-ASHBi), led by Ken-ichi Amemori, have identified a neural pathway that acts as a brake on motivation, specifically under aversive conditions, offering new insight into how the brain suppresses action when faced with unpleasantness.
The circuit in question connects two deep-brain regions: the ventral striatum (VS), which processes motivational and emotional signals, and the ventral pallidum (VP), which helps translate motivation into goal-directed actions. In primates, the VS sends inhibitory signals to the VP. The team hypothesised that during unpleasant tasks, increased VS activity may act as a brake by silencing the VP and stopping behaviour before it even starts.
To test this, the team trained two Japanese macaques on decision-making tasks. In the approach-avoidance task, monkeys were offered a combination of reward (water) and punishment (an air puff to the face), and had to decide whether to accept or reject the deal. In the approach-approach task, only rewards were on offer. Rather than focusing solely on what the monkeys chose, the team tracked whether the animals were willing to start each trial at all.
Using chemogenetics, a technique that selectively silences communication between brain regions using a viral vector and a specific drug, the researchers suppressed the VS-to-VP connection.
When the pathway was dampened during the aversive task, the monkeys became more willing to initiate trials and responded faster when choosing to accept an offer. No such changes were observed during the reward-only task, revealing that the pathway is engaged only when there is adversity.
Crucially, motivation and valuation are not the same thing. Even with the pathway suppressed, the monkeys’ actual choices didn’t change. They still weighed the air puff against the reward the same way. The brain, it seems, regulates the drive to initiate behaviour through a circuit that operates largely independently of reward calculation.
The research also showed that suppressing the VS-VP pathway could break failure ruts. When a monkey failed to initiate a trial, it became more likely to fail again on the next one, creating a downward spiral of disengagement mirroring how negative experiences can accumulate and dampen motivation over time. Suppressing the pathway interrupted this cascade, with monkeys not only initiating more trials but responding faster when they did engage.
Electrophysiological recordings confirmed the mechanism, showing that VS neurons became more active in aversive contexts and after recent failures, while VP neurons showed a slower, opposing decline. This pattern is consistent with the VS telling the VP, and by extension, the rest of the brain, to hold back. Releasing that inhibitory input restored motivational drive.
With a brain circuit now identified that specifically controls behavioural initiation, separate from reward evaluation, it opens intriguing possibilities for treating motivational deficits in depression and schizophrenia. However, the lead researcher, Ken-ichi Amemori, urges caution regarding the future therapies.
“Over-weakening the motivation brake could lead to dangerous behaviour or excessive risk-taking,” he said. “Careful validation and ethical discussion will be necessary to determine how and when such interventions should be used.”
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Source: Kyoto University; Image: Wombatzaa_Freepik
This article can be found at: Motivation under aversive conditions is regulated by a striatopallidal pathway in primates
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