From the Wall Street Journal
By (http://online.wsj.com/search/search_center.html?KEYWORDS=++++++++++++++++++++++++%3CA+HREF%3D%22%2FSEARCH%2FSEARCH_CENTER.HTML%3FKEYWORDS%3DSHIRLEY%2BS.%2BWANG%26ARTICLESEARCHQUERY_PARSER%3DBYLINEAND%22%3ESHIRLEY+S.+WANG%3C%2FA%3E++++++++++++++++++++&ARTICLESEARCHQUERY_PARSER=bylineAND)SHIRLEY S. WANG (http://online.wsj.com/SEARCH/SEARCH_CENTER.HTML?KEYWORDS=SHIRLEY+S.+WANG&ARTICLESEARCHQUERY_PARSER=BYLINEAND)
Conventionalwisdom holds that two parents are better than one. Scientists are nowfinding that growing up without a father actually changes the way yourbrain develops.
German biologist Anna Katharina Braun and others are conductingresearch on animals that are typically raised by two parents, in thehopes of better understanding the impact on humans of being raised by asingle parent. Dr. Braun's work focuses on degus, small rodents relatedto guinea pigs and chinchillas, because mother and father degusnaturally raise their babies together.
Matt Collins
Whendeprived of their father, the degu pups exhibit both short- andlong-term changes in nerve-cell growth in different regions of thebrain. Dr. Braun, director of the Institute of Biology at Otto vonGuericke University in Magdeburg, and her colleagues are also lookingat how these physical changes affect offspring behavior.
Their preliminary analysis indicates that fatherless degu pupsexhibit more aggressive and impulsive behavior than pups raised by twoparents.
In a study the researchers presented at the Society for Neurosciencemeeting in Chicago earlier this month and recently published in thejournal Neuroscience, half the degus were raised with two parents,while the others were raised by a single mother, the father having beenremoved from the cage one day after the birth of his offspring.
Dr. Braun and her colleagues found that in the two-parent families,the degu mothers and fathers cared for their pups in similar ways,including sleeping next to or crouching over them, licking and groomingthem, and playing with them. The fathers even exhibited a"nursing-type" position.
When the mother was a single parent, the frequency of herinteractions with her pups didn't change much, which means that thosepups experienced significantly less touching and interaction than thosewith two parents.
The researchers then looked at the neurons—cells that send andreceive messages between the brain and the body—of some pups at day 21,around the time they were weaned from their mothers, and others at day90, which is considered adulthood for the species.
Neurons have branches, known as dendrites, that conduct electricalsignals received from other nerve cells to the body, or trunk, of theneuron. The leaves of the dendrites are protrusions called dendriticspines that receive messages and serve as the contact between neurons.
Dr. Braun's group found that at 21 days, the fatherless animals hadless dense dendritic spines compared to animals raised by both parents,though they "caught up" by day 90. However, the length of some types ofdendrites was significantly shorter in some parts of the brain, even inadulthood, in fatherless animals.
"It just shows that parents are leaving footprints on the brain of their kids," says Dr. Braun, 54 years old.
The neuronal differences were observed in a part of the brain calledthe amygdala, which is related to emotional responses and fear, and theorbitofrontal cortex, or OFC, the brain's decision-making center.
'A Horse Without a Rider'
The balance between these twobrain parts is critical to normal emotional and cognitive functioning,according to Dr. Braun. If the OFC isn't active, the amygdala "goescrazy, like a horse without a rider," she says. In the case of thefatherless pups, there were fewer dendritic spines in the OFC, whilethe dendrite trees in the amygdala grew more and longer branches.
A preliminary analysis of the degus' behavior showed that fatherlessanimals seemed to have a lack of impulse control, Dr. Braun says. And,when they played with siblings, they engaged in more play-fighting oraggressive behavior.
In a separate study in Dr. Braun's lab conducted by post-doctoralresearcher Joerg Bock, degu pups were removed from their caregivers forone hour a day. Just this small amount of stress leads the pups toexhibit more hyperactive behaviors and less focused attention, comparedto those who aren't separated, Dr. Braun says. They also exhibitchanges in their brain.
The basic wiring between the brain regions in the degus is the sameas in humans, and the nerve cells are identical in their function. "Soon that level we can assume that what happens in the animal's brainwhen it's raised in an impoverished environment ... should be verysimilar to what happens in our children's brain," Dr. Braun says.
Other researchers, such as Xia Zhang, a senior scientist at theUniversity of Ottawa Institute of Mental Health Research, and hiscolleagues in China, have observed different consequences using voles,mouselike rodents that also naturally co-parent. (Fewer than 10% ofspecies raise their offspring with two parents.)
Voles deprived of their fathers—either from birth or later on inchildhood—exhibited more anxious behaviors and were less social,spending less time engaging with stranger voles that were placed intheir cage, according to a study by Dr. Zhang and his colleagues thatwas published in July in the journal Behavioral Processes.
Of course, the frontal cortex—where thinking and decision-makingtake place—is more complex in humans than it is in other animals. Thus,says Dr. Braun, it is important to be "really careful" aboutextrapolating the recent findings to human populations.
"The minute you get into stuff with extensive social andenvironmental components, the social differences between humans andanimals are massive," says Simon Chapple, a senior economist in thesocial policy division of the Organization for Economic Cooperation andDevelopment, the 30-country grouping of the world's largest economies.
It remains an "open verdict" whether single parenthood causes thesebad outcomes, or is merely associated with them, says Dr. Chapple.
Risk of Delinquency
Still, the prevalence of single-parenthouseholds has researchers looking at possible consequences forchildren. An OECD report found that just 57% of children in the U.S.live with both parents, among the lowest percentages of the world'srichest nations.
The report, which sparked some controversy when it was released inSeptember, found that children in single-parent households have anincreased risk of delinquency and attention deficit hyperactivitydisorder, or ADHD, as well as poorer scholastic performance.
The OECD also analyzed data from 122 separate studies and found thatthere was variability in the negative effects on children of living ina single-parent home; on average, the OECD found, the magnitude of theimpact was relatively small. On a standardized intelligence test with amedian score of 100 points, for example, a child in a single-parentfamily would be about 3.5 points worse off than a similar child in atwo-parent family, according to Dr. Chapple, who co-wrote the report.
Dr. Braun's goal for future research is to figure out whether degupups' brains can be rewired by introducing a substitute caregiver, suchas a grandmother, or whether other social and emotional enrichment canhelp "repair" the fatherless pups, she says. Human children may be sentto day care, for instance, which can help them form stable friendshipswith their peers and other adults.
The bottom line, says Dr. Braun, is that parents need to fuel theirchildren's brains with talk, touch and sensitive stimulation thatinvolves give and take.
Parents, she says, "are the sculptors of their children's brains."
By (http://online.wsj.com/search/search_center.html?KEYWORDS=++++++++++++++++++++++++%3CA+HREF%3D%22%2FSEARCH%2FSEARCH_CENTER.HTML%3FKEYWORDS%3DSHIRLEY%2BS.%2BWANG%26ARTICLESEARCHQUERY_PARSER%3DBYLINEAND%22%3ESHIRLEY+S.+WANG%3C%2FA%3E++++++++++++++++++++&ARTICLESEARCHQUERY_PARSER=bylineAND)SHIRLEY S. WANG (http://online.wsj.com/SEARCH/SEARCH_CENTER.HTML?KEYWORDS=SHIRLEY+S.+WANG&ARTICLESEARCHQUERY_PARSER=BYLINEAND)
Conventionalwisdom holds that two parents are better than one. Scientists are nowfinding that growing up without a father actually changes the way yourbrain develops.
German biologist Anna Katharina Braun and others are conductingresearch on animals that are typically raised by two parents, in thehopes of better understanding the impact on humans of being raised by asingle parent. Dr. Braun's work focuses on degus, small rodents relatedto guinea pigs and chinchillas, because mother and father degusnaturally raise their babies together.
Matt Collins Whendeprived of their father, the degu pups exhibit both short- andlong-term changes in nerve-cell growth in different regions of thebrain. Dr. Braun, director of the Institute of Biology at Otto vonGuericke University in Magdeburg, and her colleagues are also lookingat how these physical changes affect offspring behavior.
Their preliminary analysis indicates that fatherless degu pupsexhibit more aggressive and impulsive behavior than pups raised by twoparents.
In a study the researchers presented at the Society for Neurosciencemeeting in Chicago earlier this month and recently published in thejournal Neuroscience, half the degus were raised with two parents,while the others were raised by a single mother, the father having beenremoved from the cage one day after the birth of his offspring.
Dr. Braun and her colleagues found that in the two-parent families,the degu mothers and fathers cared for their pups in similar ways,including sleeping next to or crouching over them, licking and groomingthem, and playing with them. The fathers even exhibited a"nursing-type" position.
When the mother was a single parent, the frequency of herinteractions with her pups didn't change much, which means that thosepups experienced significantly less touching and interaction than thosewith two parents.
The researchers then looked at the neurons—cells that send andreceive messages between the brain and the body—of some pups at day 21,around the time they were weaned from their mothers, and others at day90, which is considered adulthood for the species.
Neurons have branches, known as dendrites, that conduct electricalsignals received from other nerve cells to the body, or trunk, of theneuron. The leaves of the dendrites are protrusions called dendriticspines that receive messages and serve as the contact between neurons.
Dr. Braun's group found that at 21 days, the fatherless animals hadless dense dendritic spines compared to animals raised by both parents,though they "caught up" by day 90. However, the length of some types ofdendrites was significantly shorter in some parts of the brain, even inadulthood, in fatherless animals.
"It just shows that parents are leaving footprints on the brain of their kids," says Dr. Braun, 54 years old.
The neuronal differences were observed in a part of the brain calledthe amygdala, which is related to emotional responses and fear, and theorbitofrontal cortex, or OFC, the brain's decision-making center.
'A Horse Without a Rider'
The balance between these twobrain parts is critical to normal emotional and cognitive functioning,according to Dr. Braun. If the OFC isn't active, the amygdala "goescrazy, like a horse without a rider," she says. In the case of thefatherless pups, there were fewer dendritic spines in the OFC, whilethe dendrite trees in the amygdala grew more and longer branches.
A preliminary analysis of the degus' behavior showed that fatherlessanimals seemed to have a lack of impulse control, Dr. Braun says. And,when they played with siblings, they engaged in more play-fighting oraggressive behavior.
In a separate study in Dr. Braun's lab conducted by post-doctoralresearcher Joerg Bock, degu pups were removed from their caregivers forone hour a day. Just this small amount of stress leads the pups toexhibit more hyperactive behaviors and less focused attention, comparedto those who aren't separated, Dr. Braun says. They also exhibitchanges in their brain.
The basic wiring between the brain regions in the degus is the sameas in humans, and the nerve cells are identical in their function. "Soon that level we can assume that what happens in the animal's brainwhen it's raised in an impoverished environment ... should be verysimilar to what happens in our children's brain," Dr. Braun says.
Other researchers, such as Xia Zhang, a senior scientist at theUniversity of Ottawa Institute of Mental Health Research, and hiscolleagues in China, have observed different consequences using voles,mouselike rodents that also naturally co-parent. (Fewer than 10% ofspecies raise their offspring with two parents.)
Voles deprived of their fathers—either from birth or later on inchildhood—exhibited more anxious behaviors and were less social,spending less time engaging with stranger voles that were placed intheir cage, according to a study by Dr. Zhang and his colleagues thatwas published in July in the journal Behavioral Processes.
Of course, the frontal cortex—where thinking and decision-makingtake place—is more complex in humans than it is in other animals. Thus,says Dr. Braun, it is important to be "really careful" aboutextrapolating the recent findings to human populations.
"The minute you get into stuff with extensive social andenvironmental components, the social differences between humans andanimals are massive," says Simon Chapple, a senior economist in thesocial policy division of the Organization for Economic Cooperation andDevelopment, the 30-country grouping of the world's largest economies.
It remains an "open verdict" whether single parenthood causes thesebad outcomes, or is merely associated with them, says Dr. Chapple.
Risk of Delinquency
Still, the prevalence of single-parenthouseholds has researchers looking at possible consequences forchildren. An OECD report found that just 57% of children in the U.S.live with both parents, among the lowest percentages of the world'srichest nations.
The report, which sparked some controversy when it was released inSeptember, found that children in single-parent households have anincreased risk of delinquency and attention deficit hyperactivitydisorder, or ADHD, as well as poorer scholastic performance.
The OECD also analyzed data from 122 separate studies and found thatthere was variability in the negative effects on children of living ina single-parent home; on average, the OECD found, the magnitude of theimpact was relatively small. On a standardized intelligence test with amedian score of 100 points, for example, a child in a single-parentfamily would be about 3.5 points worse off than a similar child in atwo-parent family, according to Dr. Chapple, who co-wrote the report.
Dr. Braun's goal for future research is to figure out whether degupups' brains can be rewired by introducing a substitute caregiver, suchas a grandmother, or whether other social and emotional enrichment canhelp "repair" the fatherless pups, she says. Human children may be sentto day care, for instance, which can help them form stable friendshipswith their peers and other adults.
The bottom line, says Dr. Braun, is that parents need to fuel theirchildren's brains with talk, touch and sensitive stimulation thatinvolves give and take.
Parents, she says, "are the sculptors of their children's brains."