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Becoming a father tends to change a man's outlook, but now scientists are showing it might also change his brain. This ScienCentral News video explains that new research in father mice reveals how time spent with their young benefits the brain.
No one can deny that becoming a dad is a life-changing experience. And despite an increase in sleepless nights and newly acquired diaper-changing duties, most would agree that it's a deeply enriching and positive one. New findings by brain researcher Kelly Lambert, professor and chair of the psychology department at Randolph-Macon College, suggest that fatherhood may change more than just a man's lifestyle – it may actually cause lasting benefits in his brain.
Lambert's research on mother rats has provided mounting evidence that motherhood benefits the brain. She found that mom rats do better on learning and memory tests than non-moms, and are also bolder, suggesting that they are protected against the damaging effects of stress.
Lambert linked these changes to the flood of hormones that accompany pregnancy and lactation, but as she wrote in Scientific American magazine, even non-mom rats given "foster" pups showed changes in these areas. Lambert got interested in the possibility that the same could be true for rodent dads. Her most recent experiments show that dads actually do outperform bachelors of the same species at locating food and show less stress in new situations, such as when encountering unfamiliar objects.
Finding a good father model in the rodent world can be tricky since, as Lambert says, "Only about six percent of mammals actually show paternal nurturing behaviors." But there are exceptions; her team worked with two closely related mouse species with vastly different responses to fatherhood. "One is a wonderful dad – we call them Mister-Moms, and the other is kind of challenged in that area – we call them deadbeat dads," says Lambert.
The Mister-Moms belong to a species called California deer mice(Peromyscus californicus) - they cuddle with and nurture pups as well as any good mother mouse. On the other hand, the "deadbeat dad" species, common deer mice(Peromyscus maniculatus), are terrified of little ones. Lambert describes their behavior saying, "'If I don't move, perhaps this critter won't see me.' Or they'll run away or attack the animal."
Male common deer mice stiffen up at the smell of a pup. image: Kelly Lambert, Randolph-Macon College
Lambert's team first compared dads with bachelors-- males who had never been dads-- in the Mister-Mom species, with results similar to her findings in rats. "We did find that the dads were better foragers and they explored a novel stimulus more than the non-dads did," says Lambert.
Then they exposed the bachelors to foster pups. Even after a short exposure period of only four days, 10 minutes a day, the virgin California deer mice responded rapidly to the baby mice. "These animals would approach, sniff, pick the animal up, seem to do everything but sing rockabye baby!" says Lambert.
In contrast, exposing common deer mice-- the "deadbeat dads"-- to pups takes precautions. The researchers put the pup under a wire mesh strainer before introducing the male. "We called it a pup tent around the lab, so that the male could not get to the pup and harm it," says Lambert. They looked for changes in two hormones known to be involved in nurturing and social behaviors: oxytocin, often nicknamed the "cuddle hormone," which is important in maternal bonding, and vasopressin, which is thought to be important in social behaviors in males.
Lambert says that in both species, exposure to the pups affected the actions of these hormones in the males. "Even the deadbeat dads… their brains were responding to being exposed to those pups," she says, "regardless of whether you were a good dad or a bad dad."
Male California deer mice tend to nurture pups, even those that don't belong to them. image: Kelly Lambert, Randolph-Macon College
Lambert says that suggests, "that just experience with the pups starts to change these areas of the brain that are involved in social and nurturing responses."
She suspects that similar changes happen in people. "I think time with the children and family unit is important for maintaining this nurturing response," she says. She says finding solid answers to questions like these could be important in decisions such as taking paternal leave.
Lambert says until more research is done in this new area, it's still a stretch to generalize from rodents to people. But she says these experimental models open up new ways to study other socially important behaviors like empathy and friendliness, and their underlying brain chemistry.