( Beyond the lineage of primates accordi...)In young mice, gregariousness seems to reside in the genes

That may well be true for many adult animals, but in a groundbreaking study researchers from the University of Wisconsin-Madison have found evidence that social interactions among young mice result from basic motivations to be with one another. What's more, the researchers say, the extent of a young mouse's gregariousness is influenced by its genetic background.

The work, reported today (April 3, 2007) in the journal Public Library of Science (PLoS) One, is important because it provides the first scientific insight that genes contribute to a novel form of natural reward - the pleasure of interacting with other juveniles. At a practical level, the new findings provide a foundation for understanding the motivations that underlie acts of altruism. Moreover, the work may also help influence the development of new, more effective drugs to treat depression, addiction and autism.

"We are quite confident it is genetic," says Jules B. Panksepp, a UW-Madison neuroscience graduate student and the lead author of the new study, which was conducted using two different strains of young mice, one gregarious in nature, the other much less so. "Their motivation to engage others varies with their genetic background; it appears to affect how young mice approach social situations."

The inbred strains of mice used in the study, once weaned, display markedly different social aptitudes. Young mice from one strain are amicable, spending much more time seeking out and interacting with other mice introduced into their environment. By controlling for a host of behavioral variables during the course of adolescent development, the researchers demonstrated specific differences in social motivations among juveniles of the two mouse strains - behavioral variations that could only be explained
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Source:University of Wisconsin-Madison