How to manipulate the brain to control maternal behavior in females and reduce aggression in males

October 7, 2015, Weizmann Institute of Science

Most female mammals give birth and care for their offspring, while the males often breed with multiple partners and play little role in parenting once the mating is over. Yet researchers have had a hard time pinpointing where, exactly, in the brain these differences between the sexes are located and how they translate into behavior. The extent of "hardwired parental behavior" is hotly disputed.

In new research published in Nature, Dr. Tali Kimchi and her graduate student Niv Scott, in collaboration with Dr. Ofer Yizhar and Dr. Matthias Prigge, a postdoctoral fellow in his lab, all of the Weizmann Institute's Neurobiology Department, offer new insight into this issue. This research shows that same network of brain cells operates differently in male and .

Female mice, even those that have never had pups, act in ways that can be defined as maternal. They will carry a pup left in the corner of the cage back to the nest, for example, and spend time grooming a newborn. This tendency becomes amplified once those mice turn into mothers. Males, in contrast, are generally aggressive and territorial. They may ignore strange pups or else violently attack them. However, males will become parental for a short period after mating with a female, starting around the birth of their pups.

To investigate how the brain manages parental behavior, the researchers zeroed in on a small structure in part of the brain known as the hypothalamus, called the anteroventral preventricular nucleus, or AVPV, which is larger in female mice than in males. The team was particularly interested in certain that express a protein known as tyrosine hydroxylase, or TH, which is required for the production of dopamine - a chemical messenger in the brain. They observed that specific TH-containing neurons are more numerous in mothers than in either virgin females or any males. This hinted that these neurons, even though they are shared by both sexes, could drive parental care in females while serving a different function in males.

Using advance genetic and neuro-biochemical tools, the team first increased and then decreased the amount of TH in both adult male and female mice - just in neurons of this particular brain region. Then the researchers recorded how these changes affected the parenting styles of the mice. The team also employed optogenetic technology, in which neurons are activated by light, to precisely manipulate the activity of TH-containing neurons - literally, at the flip of a light switch.

The researchers found they were especially able to trigger maternal actions in female mice - both virgins and mothers - by elevating the TH levels in these neurons. Also, brief optogenetic activation - even a few minutes - was all that was required to get a female to hurry to the corner of the cage to carry a pup back to her nest. Further tests revealed that these manipulations enhanced blood levels of oxytocin - a hormone associated, among other things, with lactation and female reproductive behavior in general. Decreasing the number of TH-containing neurons in females lowered their levels of oxytocin and severely impaired their maternal instincts.

When the scientists used optogenetics to activate TH-containing neurons in male mice, there was no effect on oxytocin levels or pup-caring. However, surprisingly, there was a significant drop in aggressive behaviors toward unfamiliar pups and adult males, both of which they would normally have attacked. Decreasing the number of TH-containing neurons, on the other hand, led to a profound increase in the males' aggression toward both.

"By controlling the amount and activities of these unique neurons, we were able to manipulate the maternal behavior of the females and the aggression of the males, says Kimchi. "Our results hint that arises from neuronal networks that are largely hard-wired. These are different from those of , and they are at least partly regulated by the hormone oxytocin."

These findings may, in the future, provide insight into the ways that male and female brains function when it comes to such conventional gender-related activities as tending to infants, and other innate reproductive and social behaviors. Kimchi hopes that this discovery may ultimately advance our understanding of the biological factors that contribute to mental disorders, which have a social aspect, as well as gender differences. These include postpartum depression, aggression and autism spectrum disorders.

Explore further: Parenting in the animal world: Turning off the infanticide instinct

More information: A sexually dimorphic hypothalamic circuit controls maternal care and oxytocin secretion, Nature 525, 519–522 (24 September 2015) DOI: 10.1038/nature15378

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gkam
1.6 / 5 (7) Oct 07, 2015
Any time we can reduce the aggression of the maladjusted it is a good idea. We can see some of it in these fora, with snipers attacking those who have comments to make.
Whydening Gyre
3.7 / 5 (7) Oct 07, 2015
How do we know if it isn't already being done via food, bottled water or even the air we breath?

Just a little somethin' to make ya go - hmmm...:-)
gkam
3 / 5 (6) Oct 07, 2015
We are actually controlled by the chemical secretions of active agents in the brain, responsible for our emotions.

I get my daily dose of Oxytocin by taking care of my grandchildren. We are afforded pleasure for life-affirming behavior.
TheGhostofOtto1923
2.3 / 5 (6) Oct 07, 2015
We are actually controlled by the chemical secretions of active agents in the brain, responsible for our emotions.

I get my daily dose of Oxytocin by taking care of my grandchildren
Shudder
TheGhostofOtto1923
2 / 5 (4) Oct 07, 2015
"Most female mammals give birth and care for their offspring, while the males often breed with multiple partners and play little role in parenting once the mating is over"

-Theyve left out a very important part of this equation... while a males preferred strategy is to impregnate as many females as possible, the females strategy is to select the very best donor for each and every child she wishes to bear.

And the best way to discern quality in a male is to compel him to compete with other suitors.

In the wild the most aggresssive males would be selected for. But humans emerged from the primate pool in the context of the tribe.

Natural male and female mating prerogatives are directly in conflict with tribal harmony and unity.
cont>
TheGhostofOtto1923
2.9 / 5 (8) Oct 07, 2015
"Rude tribes and... civilized societies... have had continually to carry on an external self-defence and internal co-operation - external antagonism and internal friendship. Hence their members have acquired two different sets of sentiments and ideas, adjusted to these two kinds of activity... A life of constant external enmity generates a code in which aggression, conquest and revenge, are inculcated, while peaceful occupations are reprobated. Conversely a life of settled internal amity generates a code inculcating the virtues conducing to a harmonious co- operation (Spencer, 1892)

-We can see this effort reflected in the woorlds religions. Moslems want to cover their women from head to toe to minimize their natural desire to entice other males to compete. Some of the worst social crimes are those of infidelity.

Moslem men all wear full beards and dress similarly in order to standardize their appearance.

These standards prevail in all the surviving state-sponsored religions.
gkam
1.8 / 5 (5) Oct 07, 2015
Religion? Sounds like Fascism. Sounds like control freaks. Sounds like cowards.
TheGhostofOtto1923
2 / 5 (4) Oct 07, 2015
Religion? Sounds like Fascism. Sounds like control freaks. Sounds like cowards.
Sounds like idiot 70s t shirt slogans.

"... this suggests a genetic restriction to what we have called the Juvenile Dictionary. Not only are they using extremely restricted definitions, they cannot, by virtue of the way their brains work, do otherwise. Virtually all of the research on psychopaths reveals an inner world that is banal, sophomoric, and devoid of the color and detail that generally exists in the inner world of normal people...
colbey
5 / 5 (1) Oct 10, 2015
These standards prevail in all the surviving state-sponsored religions.

interesting. do you have references, or is it a personal hypothesis or observation? i'm not questioning that 3 of the major world religions share a patriarchal background. please define "state-sponsored religions." i'm unsure if hinduism, buddhism, or some...Native American religions are included.

Moslems want to cover their women from head to toe to minimize their natural desire to entice other males to compete.

this is a novel way of analyzing this particular behavior/custom. exactly whose desires do you believe it is meant to minimize? with the word "entice," it seems as though you are saying covering women in public minimizes the WOMEN'S "biological drive" to attract the most aggressive male. (quotes used because this is a paraphrase of your theory.)

<.cont.>>
colbey
5 / 5 (1) Oct 10, 2015
<.cont.>
Moslem men all wear full beards and dress similarly in order to standardize their appearance.

ignoring the faint whiff of stereotyping, how does this backup your premise of "males needing to compete with other males"? alternate wording--how does this minimize male aggression?

it almost seems as though you are saying that both covering the women and homogenizing the men act to minimize the "biological drive" of women to attract an aggressive male.
which, btw, i believe is not always true "in the wild" (as you say).

humans emerged from the primate pool in the context of the tribe. Natural male and female mating prerogatives are directly in conflict with tribal harmony and unity.

i agree with the first sentence.
but after tens of thousands of years (probably a minimum), wouldn't these traits that are so antithetical to humans' chosen mode of organization have evolved to some degree, if not been completely, or nearly, removed from the gene pool?
julianpenrod
1.5 / 5 (6) Oct 10, 2015
A well known phenomenon, that females trend to show mothering tendencies even if they have never had a child. Girls play with dolls, among other things, to indulge mothering tendencies. When they get pregnant, their systems flood with hormones, even early on, which would tend to create nurturing, protective behavior. Which, again, brings up the question of women overcoming all those tendencies and having an abortion by craven whim, out of spite for the man or, as seems often the case, selling the fetal body parts for money. What are considered normal women don't throw babies into trash baskets because they want a career, in many ways, a fetus can still be like a baby in a woman's consciousness. Women who have abortion by craven whim, then, seem to have the same qualities as women who boil their babies in hot water on stove tops, burn them alive in ovens or shake them until their brains explode.
venus666
1 / 5 (1) Oct 12, 2015
In past, I thought that there are different brain structure between men and women for they think in very different way. But from this passage, even the same brain cells work differently between men and women. So how to find a way for both men and women to have the same thoughts
jeffensley
5 / 5 (1) Oct 12, 2015
So how to find a way for both men and women to have the same thoughts


And why in the world would you want to do that?

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