Life isn’t always easy for little mouse pups: Hours to days after they are born, the squirmy babies, who can’t hear or see, can roll or stumble away from their nest. Cold and lonely, they call out to their mother. Luckily, Mom snaps into action to ensure the adventures of the little ones are short-lived. Grabbing each pup by the skin on their backs, Mama mouse brings each baby back home to safety.
The mom’s behavior is innate, burnt into the mouse brain, and requires no training. But where in the brain does it happen and how does the brain process or execute it? And what happens in those rare cases when the animal brain doesn’t properly execute such behavior? That’s what Stephen Shea is trying to answer in mice, with hopes that it may someday be applicable to humans.
Shea, an associate professor at Cold Spring Harbor Laboratory, discovered that this innate mothering behavior corresponds to the firing of cells in a region of the brain called locus coeruleus, a cluster of cells that can be found in the brainstem of all vertebrates. Locus coeruleus is also the source of noradrenaline, a chemical that affects some key brain functions.
Shea’s work has greater implications. He hopes that understanding the brain circuits that facilitate this very simple action could be a window into how disruptions in wiring affect social behavior, and a key into understanding inappropriate social interactions, such as those observed in people with autism spectrum disorders. And it may even shed some light on the iconic debate about whether creatures are shaped by nature or nurture.
“Something must have changed in the brain to cause the animal to show different kinds of behaviors toward the pup.”
When social animals encounter one another, they interact by taking in sensory inputs (such as sounds and smells), processing them in the brain, and responding appropriately. In popular conception, there are two competing factors that determine animal or human behavior, hard wiring and learned traits, or as it’s commonly known nature versus nurture. Neuroscientists and biologists, however, don’t think of animal responses as being the product of one or the other but an interplay between the two. One of the ways to understand this back-and-forth in the brain is by working backward, through the lens of behaviors that can be innately expressed, such as the maternal ones in mice, and then how the innate expression of that behavior is further modulated by learning.
“We study social communication behavior between mice,” Shea says. “Mice talk to one another, they smell one another, and they can learn a lot from that. We want to understand that process, how that’s represented in the brain [and] what the mechanistic controls of those beh
