Intriguingly, the Wisconsin researchers also found that young mice from the gregarious strain seek environments that predict the possibility of a social encounter and avoid places where they have experienced social isolation.
"They like company. That's the point," says Garet Lahvis, of the gregarious strain of mouse. Lahvis is a professor of surgery in the UW School of Medicine and Public Health and the senior author of the new study.
Performing under the dim glow of red lights to simulate the nocturnal environment when mice are most active, the sociability of test mice was assessed when they were reunited with their former cage mates. At the same time, the researchers tuned in to the ultrasonic chattering that mice use to communicate with each other.
For the more socially predisposed animal, gregariousness was the order of the day, says Lahvis: "A young mouse will seek social interaction and avoid isolation. The social life of these animals is a rich integration of behavior, vocalizations and positive emotional experience."
The level of social interplay of the two strains of mice, Panksepp and Lahvis note, is mirrored in their vocalizations, and the differences in vocalization between the two types of mouse also segregated with genetic background.
"We identified associations between types of mouse vocalizations and the extent of their social interactions," says Lahvis. "There is an association between high-pitched calls in mice and positive experience. The quality and quantity of the call are tightly associated with the nature of the interaction itself."
As the mice neared sexual maturity, the genetic influence on social behavior ebbed and the animals became much more responsive to social cues such as gender, according to Lahvis.
"As they get older, they take on the [behavioral] characteristics associated with gender," Lahvis explains. "The initial genetic pred
Source:University of Wisconsin-Madison