Individual personalities of mice are influenced by social relations, study finds

Aug. 6 (UPI) -- All animals exhibit individuality, including mice. Individual mice showcase unique personalities and behavioral traits, according to new research.

Previous research showed individuality is influenced by genetics and developmental phenomena. Now, scientists have shown social relations also affect individuality.

Biologists at the French National Center for Scientific Research and Sorbonne University were able to study the social relations among groups of mice, as well as the personalities of individuals, using an experimental testing device.

The innovative device allowed scientists to test individual mice without directly intervening. The device consisted of a T-shaped maze attached to two separate communal living spaces. The maze featured two arms, one leading to unaltered water, another leading to sugar water. Scientists regularly switched the placement of the two types of water.

Scientists found the mice reacted two different ways. Some mice returned to the same arm, over and over. Other mice frequently varied their route.

Researchers recognized a correlation between the activity of dopamine-producing neurons and individual behaviors. Mice that varied their routing the most exhibited lower dopaminergic activity.

To better understand the behavioral differences, scientists reorganized the mice among the two communal living spaces. Scientists organized the mice by personality type. Mice that varied their routing in one living space and mice that choose that same arm in the other living space.

When scientists repeated the testing, they found the individual behavioral traits were redistributed across each group, with roughly half the mice in each group adopting the opposite trait. A shift in dopaminergic activity accompanied the behavioral change.

The research, published Monday in the journal Nature Communications, showed individuality is socially influenced.

"Individuality can rapidly change upon social challenges, and does not just depend on the genetic status or the accumulation of small differences throughout development," researchers wrote.

More research is needed to understand how group relations affect behavioral changes among individual mice.