July 15, 2026
TOKYO – The brain mechanisms for rewriting the desire to approach or avoid a specific individual based on experience were revealed through experiments on mice by a team that included researchers from the University of Tokyo.
The findings were published in the journal Science.
In its Friday announcement, the team also said it successfully eliminated avoidance behavior toward a disliked individual, noting that the research could lead to the development of treatments for depression and other conditions.
The experiments were conducted using multiple mice that had become familiar with one another after spending time in the same area.
One of the mice was given a drug to increase its aggressiveness and was made to attack another mouse. The mouse that was attacked subsequently began avoiding that specific mouse.
The team analyzed the functioning of neurons in the brain of the attacked mouse, focusing on specific areas of the hippocampus, which is involved in memory processing, and the amygdala, which governs the fear response. Weakening the connections between neurons that transmit information from the hippocampus to the amygdala successfully eliminated the avoidance behavior toward the attacker mouse.
Furthermore, the team found that when they stimulated neurons storing the memory of a different individual while applying an unpleasant electrical shock, the mouse began avoiding that individual as well, despite never having been attacked by it.
“We have begun to understand the mechanism that rewrites the evaluation of like or dislike based on experience, while the memory of who the individual is remains intact,” said University of Tokyo Prof. Teruhiro Okuyama, an expert in behavioral neuroscience.
University of Toyama Prof. Kaoru Inokuchi, an expert in neuroscience, noted that while the findings cannot yet be applied to humans, they offer a crucial clue for developing ways to treat and prevent social anxiety disorder and depression.