PREGNANT WOMAN
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What turns a young female concerned mainly about herself into a good mother who will make sure her offspring survive in an otherwise hostile world? The bodily changes of childbearing are obvious, but as we are discovering, the changes in the brain are no less dramatic.
The maternal brain is a formidable object, a singular entity forged by hormones, neurochemicals, and exposure to the ravening demands and irresistible cuteness of offspring. During pregnancy, the female brain is effectively revving up for the difficult tasks that await. A mother-to-be may most notice her cravings for ice cream and pickles, but inside her head, a transformation is afoot in fundamental functions ranging from attention to memory. As an intriguing new paper demonstrates, even her sensitivity to others' emotions increases.
Before we describe the new paper, let us contemplate the maternal brain in all of its wet majesty. Among its remarkable changes are those that allow the mother to focus on her infant in the persistent attempt to puzzle out the child’s needs and wants. As any parent knows, the infant is inscrutable – indeed, the child remains so for much of the parent’s life – and intuition is the mother’s best friend. The parent tests hypotheses: Is the baby hungry? Tired? A sensitized brain facilitates these “experiments.” In humans, rodents and other animals, we find data showing that the mother’s interest in, and motivation toward young increases dramatically as pregnancy nears term, and still further immediately following birth.
Underlying such change is a manifest shift in neuronal size, activity and capacity. Neurons in the part of the brain that largely regulate maternal behavior, called the medial preoptic area (mPOA), grow impressively during late pregnancy, increasing the protein-synthesizing capabilities of the cell. Like a race-car burning rubber before the green light, these mPOA neurons are readying themselves to respond to offspring stimuli with appropriate and sensitized impulses.
Further, in another brain region, the hippocampus, neurons are undergoing changes of another sort, leading to increases in the concentration of tiny projections on the surface of dendrites, called dendritic spines. These dendritic spines provide more neuronal surface and are believed to regulate inter-neuronal commerce. That the spines are increasing in the hippocampus, which controls learning and memory, suggests a possible function: enhancing memory, particularly spatial memory, that may be required of the new mother.
Fittingly, many data from numerous labs show that females with offspring have an increased facility for remembering the location of food caches and rewards in a variety of spatial environments. These females -- particularly multiparous females, those with two or more pregnancies under their belts -- are especially good at these tasks. Now, think about why: a mother that must leave her nest to forage for food – or her home for work – exposes both herself and her young to risk of predators and may benefit from an enhancement to her foraging skills or to the economy of her behavior, in general. The cost:benefit ratio decreases if she can find food and get back as quickly as possible to her lonely and vulnerable offspring.
In their recent paper, Rebecca Pearson of the University of Bristol’s Academic Unit of Psychiatry and her co-authors add fuel to the race-car-burning-rubber theory. They find that not only are neurons ramping up their own activity levels, but that the hormones estrogen and progesterone are also intensifying emotive activity, helping mothers become more focused on their offspring and their offspring’s myriad cues.
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13 Comments
Add CommentVery interesting article. One thing that occurred to me when reading it is that if oestrogen and progesterone help the brains of mothers develop so that they are more able to recognise emotions in the faces of others - is that why autism is more common in boys?
Reply | Report Abuse | Link to thisClare,
Reply | Report Abuse | Link to thisJust wanted to say you put forth an interesting suggestion about whether that is associated with the higher prevalence of autism among boys.
Looking forward to replies from others that address this.
Best.
Clare,
Reply | Report Abuse | Link to thisOne of the reasons that autism has a higher prevalence rate in boys than girls is because there is a genetic link. Any developmental disorder that has a genetic component has a higher prevalence in boys than in girls (eg. ASD, ADHD, etc.) Check it out. It has to do with which genes "show" and which genes are "masked". If you have 2 X chromosomes, the "bad" genes on one chromosome will be hidden by the good genes on the other one, however when you have 1 X and 1 Y, you don't have that "back-up" chromosome to "mask" the "bad" ones... make sense?
I already know what the dramatic hormonal fluctuations of pregnancy and postpartum can do to a woman's mental and emotional state. What I wanna know is what the heck is going on now, with the dramatic hormonal fluctuations of perimenopause!
Reply | Report Abuse | Link to thisInteresting partial research. Now how about research on the brains of men while their spouse is pregnant to see what changes naturally occur? Most men radically change their behavoir when they become daddies (unless they are real jerks). Do their brains get re-wired also or are they already prepped for baby duty by the time they are able to be fathers?
Reply | Report Abuse | Link to thisI have heard or read all sorts of theories about the impact of hormones on autism but I have yet to see any real research that holds up under testing.
We are just barely scratching the surface of understanding how the body works. We need a lot more research funding in tthe sciences and a lot less politics.
dear sicily726,
Reply | Report Abuse | Link to thisthe climacteric to which you refer represents a natural but significant withdrawal of both hormones and associated neurotransmitters and the neurotrophic (growth-promoting) factors that depend on them. it is not unlike a field of flowers, formerly dependent on a certain steady level of water and nutrients, responding to a drought. the symptoms you describe are reflective of a number of changes, all normal and natural, if unpleasant, and research has shown the vital role that hormones play in maintaining such brain and body basal activities of the sort that you cite. some data show that parity protects against, in part, such changes, but more work needs to be done. best of luck.
dear bucketofsquid ,
Reply | Report Abuse | Link to thisyou are correct insofar as your reference to the changes that men undergo as they transition to fatherhood; there are neural changes that occur that rival what is observed in the female. they are on a continuum with the female transitioning to mother, but they have, if you will, a grey ceiling, preventing much of their movement beyond certain limits. just as the mother has a uterus and mammary glands that indicate the primary role she plays in the reproductive events, the father may want to be a "mother," in the sense that the overwhelming emotion and motivation that usually accompany that state is an attractive goal, but the biology is just not there: the spirit is willing, but the flesh is absent...
It seems to me that the reason people and events are "inscrutable" and we have to rely on intuition is that we are less in touch with our unconsciousness than we could be and should be. It's a matter of perception in a larger context, and makes us focus on the wrong problem.
Reply | Report Abuse | Link to thisThis is not a satisfactory answer. Autoimmune disorders mostly affect women and they do have a genetic component too.
Reply | Report Abuse | Link to thisP.S.: Clare raises an important issue in the role of hormones. It has been shown that oxytocin (the "love hormone") expressed more in women can be used beneficially to treat autistic men.
Reply | Report Abuse | Link to thisThis is not a satisfactory answer. Autoimmune disorders mostly affect women and they do have a genetic component too.
Reply | Report Abuse | Link to thisRegarding the "downside" of these hormones: this research is describing only the opening bars of a complex hormonal dance. In nature, and when we avoid the medicalization of birth and baby feeding, the hormones of pregnancy are followed by an even more intense surge of oxytocin during labor and birth, which is lacking when labors are induced or augmented via artificial oxytocin (a.k.a. pitocin, which can't cross the blood-brain barrier) and when pharmaceutical comfort measures interfere in the endorphin-oxytocin cycle of normal labor. After birth, breastfeeding continues to stimulate release of oxytocin along with prolactin, which is not only a calming hormone but also a potent suppressor of the menstrual cycle, thus allowing a woman's body gradually to come down off the hormonal highs of pregnancy over the course of a year or more as baby nurses and then gradually weans to solid foods.
Reply | Report Abuse | Link to thisOnce we understand the normal flow of hormone states from pregnancy through birth through breastfeeding and gradual weaning, it's no surprise that hijacking the normal hormonal processes of birth and breastfeeding causes many, many women to drop off a cliff into postpartum depression. This is not a downside of the hormones of pregnancy. It's a downside of the medicalization of birth and low rates of breastfeeding.
I think men undergo "daddy brain" changes due to pheromones produced by the pregnant female. Some more so than others. There is a phenomenon of the "pregnant male" during his mate's pregnancy.
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