AsianScientist (Jan. 28, 2026) – Social life, whether in a corporate office or an animal community, depends on a constantly shifting hierarchy. Every competitive encounter can influence an individual’s standing, and past experience often tips the balance. This dynamic is known as the winner-loser effect, where success tends to reinforce dominance, while defeat prompts retreat. Responding appropriately to a setback is vital since a misstep can destabilise group relationships. This has led scientists to suspect that the brain may be hard-wired to treat negative encounters as particularly influential when shaping future behaviour.
In a study published in iScience, researchers from the Okinawa Institute of Science and Technology (OIST) have identified the neural mechanism that controls the social dynamics in male mice. Their findings reveal that the brain uses separate circuits for learning from winning versus losing, with the “loser’s brain” relying on a specific, vulnerable mechanism.
To study social rank, the researchers used dominance tube tests (DTTs), where two mice enter a narrow tube from opposite ends, and the one that pushes the other out is designated the winner. After establishing stable ranks in their home cages, the mice faced an external challenge against equally ranked opponents from other cages.
The results confirmed the classic winner-loser effect. When high-ranking, dominant mice lost to other dominants, they subsequently dropped in rank back in home cages, often losing to previously subordinate cage-mates. Conversely, when low-ranking, subordinate mice won, they became more likely to win against higher-ranked cage-mates.
“You may think that being dominant in the animal kingdom is all about physical attributes, like size. But we’ve found that it seems to be a choice, based on previous experience,” said Jeffery Wickens, professor and head of the Neurobiology Research at OIST. “The brain circuitry involved in these decisions is well conserved between mice and humans, so there are likely useful parallels to be drawn.”
The researchers traced this ‘choice’ to the dorsomedial striatum (DMS), a brain region known for regulating behavioural flexibility. Located inside this area is a tiny, specialised group of brain cells called cholinergic interneurons (Chls).
When the researchers removed these Chls using a selective ablation technique and repeated the dominance competition, the impact was surprising. The mice that had their Chls lesioned no longer displayed the loser effect. Dominant mice that lost external defeat maintained their rank when they returned to their home cages, suggesting their brains were no longer registering the loss as a cue to change strategy.
Importantly, removing these neurons had no effect on the winner effect. Subordinate mice who won external competitions still increased their rank, just like the control mice.
“Removing the Chls disrupted the ‘loser effect’—mice did not reduce in dominance based on past experiences of losing. But no change was seen in the winner effect, suggesting that different brain circuitry is involved in these social behaviours,” explained Mao-Ting Hsu, lead author of the study.
According to these researchers, the winner effect likely operates as a reward-based learning process. In contrast, the loser effect appears to depend on a specific decision-making process connected to the Chls in the DMS, acting as a switch that tells a dominant animal to abandon its old ‘winning’ strategy after a loss.
Although the study was conducted in male mice, the findings point to general principles underlying flexible social behaviour. “Because mice and humans share similar brain structures, these studies might help us unlock future insights into the more complex social dynamics of our own species,” said Hsu.
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Source: Okinawa Institute of Science and Technology; Image:
This article can be found at: Cholinergic interneurons of the dorsomedial striatum mediate winner-loser effects on social hierarchy dynamics in male mice
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