The Mom Brain

Recently, I read an opinion titled When I Became A Mother, Feminism Let Me Down. The gist of it was that some feminists, while empowering women and girls to be anything they want to be and to do anything a man or a boy does, they fail in uplifting the motherhood aspect of a woman’s life, should she choose to become a mother. In other words, even (or especially, in some cases) feminists look down on the women who chose to switch from a paid job and professional career to an unpaid stay-at-home mom career, as if being a mother is somehow beneath what a woman can be and can achieve. As if raising the next generation of humans to be rational, informed, well-behaved social actors instead of ignorant brutal egomaniacs is a trifling matter, not to be compared with the responsibilities and struggles of a CEO position.

Patriarchy notwithstanding, a woman can do anything a man can. And more. The ‘more’ refers to, naturally, motherhood. Evidently, fatherhood is also a thing. But the changes that happen in a mother’s brain and body during pregnancy, breastfeeding, and postpartum periods are significantly more profound than whatever happens to the most loving and caring and involved father.

Kim (2016) bundled some of these changes in a nice review, showing how these drastic and dramatic alterations actually have an adaptive function, preparing the mother for parenting. Equally important, some of the brain plasticity is permanent. The body might spring back into shape if the mother is young or puts into it a devilishly large amount of effort, but some brain changes are there to stay. Not all, though.

One of the most pervasive findings in motherhood studies is that hormones whose production is increased during pregnancy and postpartum, like oxytocin and dopamine, sensitize the fear circuit in the brain. During the second trimester of pregnancy and particularly during the third, expectant mothers start to be hypervigilent and hypersensitive to threats and to angry faces. A higher anxiety state is characterized, among other things, by preferentially scanning for threats and other bad stuff. Threats mean anything from the improbable tiger to the 1 in a million chance for the baby to be dropped by grandma to the slightly warmer forehead or the weirdly colored poopy diaper. The sensitization of the fear circuit, out of which the amygdala is an essential part, is adaptive because it makes the mother more likely to not miss or ignore her baby’s cry, thus attending to his or her needs. Also, attention to potential threats is conducive to a better protection of the helpless infant from real dangers. This hypersensitivity usually lasts 6 to 12 months after childbirth, but it can last lifetime in females already predisposed to anxiety or exposed to more stressful events than average.

Many new mothers worry if they will be able to love their child as they don’t feel this all-consuming love other women rave about pre- or during pregnancy. Rest assured ladies, nature has your back. And your baby’s. Because as soon as you give birth, dopamine and oxytocin flood the body and the brain and in so doing they modify the reward motivational circuit, making new mothers literally obsessed with their newborn. The method of giving birth is inconsequential, as no differences in attachment have been noted (this is from a different study). Do not mess with mother’s love! It’s hardwired.

Another change happens to the brain structures underlying social information processing, like the insula or fusiform gyrus, making mothers more adept at self-motoring, reflection, and empathy. Which is a rapid transformation, without which a mother may be less accurate in understanding the needs, mental state, and social cues of the very undeveloped ball of snot and barf that is the human infant (I said that affectionately, I promise).

In order to deal with all these internal changes and the external pressures of being a new mom the brain has to put up some coping mechanisms. (Did you know, non-parents, that for the first months of their newborn lives, the mothers who breastfeed must do so at least every 4 hours? Can you imagine how berserk with sleep deprivation you would be after 4 months without a single night of full sleep but only catnaps?). Some would be surprised to find out – not mothers, though, I’m sure – that “new mothers exhibit enhanced neural activation in the emotion regulation circuit including the anterior cingulate cortex, and the medial and lateral prefrontal cortex” (p. 50). Which means that new moms are actually better at controlling their emotions, particularly at regulating negative emotional reactions. Shocking, eh?

140 mom brain1 - Copy

Finally, it appears that very few parts of the brain are spared from this overhaul as the entire brain of the mother is first reduced in size and then it grows back, reorganized. Yeah, isn’t that weird? During pregnancy the brain shrinks, being at its lowest during childbirth and then starts to grow again, reaching its pre-pregnancy size 6 months after childbirth! And when it’s back, it’s different. The brain parts heavily involved in parenting, like the amygdala involved in the anxiety, the insula and superior temporal gyrus involved in social information processing and the anterior cingulate gyrus involved in emotional regulation, all these show increased gray matter volume. And many other brain structures that I didn’t list. One brain structure is rarely involved only in one thing so the question is (well, one of them) what else is changed about the mothers, in addition to their increased ability to parent?

I need to add a note here: the changes that Kim (2016) talks about are averaged. That means some women get changed more, some less. There is variability in plasticity, which should be a pleonasm. There is also variability in the human population, as any mother attending a school parents’ night-out can attest. Some mothers are paranoid with fear and overprotective, others are more laissez faire when it comes to eating from the floor.

But SOME changes do occur in all mothers’ brains and bodies. For example, all new mothers exhibit a heightened attention to threats and subsequent raised levels of anxiety. But when does heightened attention to threats become debilitating anxiety? Thanks to more understanding and tolerance about these changes, more and more women feel more comfortable reporting negative feelings after childbirth so that now we know that postpartum depression, which happens to 60 – 80% of mothers, is a serious matter. A serious matter that needs serious attention from both professionals and the immediate social circle of the mother, both for her sake as well as her infant’s. Don’t get me wrong, we – both males and females – still have a long way ahead of us to scientifically understand and to socially accept the mother brain, but these studies are a great start. They acknowledge what all mothers know: that they are different after childbirth than the way they were before. Now we have to figure out how are they different and what can we do to make everyone’s lives better.

Kim (2016) is an OK review, a real easy read, I recommend it to the non-specialists wholeheartedly; you just have to skip the name of the brain parts and the rest is pretty clear. It is also a very short review, which will help with reader fatigue. The caveat of that is that it doesn’t include a whole lotta studies, nor does it go in detail on the implications of what the handful cited have found, but you’ll get the gist of it. There is a vastly more thorough literature if one would include animal studies that the author, curiously, did not include. I know that a mouse is not a chimp is not a human, but all three of us are mammals, and social mammals at that. Surely, there is enough biological overlap so extrapolations are warranted, even if partially. Nevertheless, it’s a good start for those who want to know a bit about the changes motherhood does to the brain, behavior, thoughts, and feelings.

Corroborated with what I already know about the neuroscience of maternity, my favourite takeaway is this: new moms are not crazy. They can’t help most of these changes. It’s biology, you see. So go easy on new moms. Moms, also go easy on yourselves and know that, whether they want to share or not, the other moms probably go through the same stuff. You’re not alone. And if that overactive threat circuit gives you problems, i.e. you feel overwhelmed, it’s OK to ask for help. And if you don’t get it, ask for it again and again until you do. That takes courage, that’s empowerment.

P. S. The paper doesn’t look like it’s peer-reviewed. Yes, I know the peer-reviewing publication system is flawed, I’ve been on the receiving end of it myself, but it’s been drilled into my skull that it’s important, flawed as it is, so I thought to mention it.

REFERENCE: Kim, P. (Sept. 2016). Human Maternal Brain Plasticity: Adaptation to Parenting, New Directions for Child and Adolescent Development, (153): 47–58. PMCID: PMC5667351, doi: 10.1002/cad.20168. ARTICLE | FREE FULLTEXT PDF

By Neuronicus, 28 September 2018

How long does it take for environmental enrichment to show effects?

From funnyvet.
From funnyvet.

Environmental enrichment is a powerful way to give a boost to neurogenesis and alleviate some anxiety and depression symptoms. For the laboratory rodents, who spend their lives in cages with water and food access, environmental enrichment can refer to as little as a toy or two or as much as large room colonies with different size tubes, different levels to explore, nesting materials, plenty of toys with various shapes, textures, and colors, exercise wheels, and even the occasional fruit or peanut butter snack. But for how long does a mouse need to be exposed to enrichment to show cognitive and emotional improvement?

Leger et al. (2015) ran several anxiety, depression, and long-term memory tests in mice who have been exposed to environmental enrichment for 24 h, 1, 3, or 5 weeks. Although 24 h exposure was enough to improve memory, only after 3-week exposure some anxiety behaviors were attenuated. No effect on depressive behaviors or coticosterone levels, which may be due to that particular strain of mouse (several other studies found that environmental enrichment ameliorates depressive symptoms in other mice strains and rats). The 3-week exposure also increased the levels of serotonin in the frontal cortex. Only after 5-eweek exposure there was a significant survival rate of the hippocampal new cells. Of note, these were normal mice, i.e. they were not suffering from any disorder prior to exposure.

Mice raised in an impoverished environment (a) show less dendrite growth (c) than do mice raised in an enriched environment (b, d). Copyright: BSCS.
Mice raised in an impoverished environment (a) show less dendrite growth (c) than do mice raised in an enriched environment (b, d). Copyright: BSCS.

The findings give us a nice timeline for environmental enrichment to show its desired effects. But… if there are differences in the timeline and effects of environmental enrichment exposure from mouse strain to mouse strain, then what can we say for humans? Probably not much, unfortunately. As the ad nauseam overused phrase goes at the end of so many papers, ‘more research is needed to elucidate this problem’.

Reference: Leger M, Paizanis E, Dzahini K, Quiedeville A, Bouet V, Cassel JC, Freret T, Schumann-Bard P, & Boulouard M. (Nov 2015, Epub 5 Jun 2014). Environmental Enrichment Duration Differentially Affects Behavior and Neuroplasticity in Adult Mice. Cerebral Cortex, 25(11):4048-61. doi: 10.1093/cercor/bhu119. Article | FREE PDF

By Neuronicus, 1 November 2015

It’s what I like or what you like? I don’t know anymore…

The plasticity in medial prefrontal cortex (mPFC) underlies the changes in self preferences to match another's through learning. Modified from Fig. 2B from Garvert et al. (2015)
The plasticity in medial prefrontal cortex (mPFC) underlies the changes in self preferences to match another’s, through learning. Modified from Fig. 2B from Garvert et al. (2015), which is an open access article under the CC BY license.

One obvious consequence of being a social mammal is that each individual wants to be accepted. Nobody likes rejection, be it from a family member, a friend or colleague, a job application, or even a stranger. So we try to mould our beliefs and behaviors to fit the social norms, a process called social conformity. But how does that happen?

Garvert et al. (2015) shed some light on the mechanism(s) underlying the malleability of personal preferences in response to information about other people preferences. Twenty-seven people had 48 chances to make a choice on whether gain a small amount of money now or more money later, with “later” meaning from 1 day to 3 months later. Then the subjects were taught another partner choices, no strings attached, just so they know. Then they were made to chose again. Then they got into the fMRI and there things got complicated, as the subjects had to choose as they themselves would choose, as their partner would choose, or as an unknown person would choose. I skipped a few steps, the procedure is complicated and the paper is full of cumbersome verbiage (e.g. “We designed a contrast that measured the change in repetition suppression between self and novel other from block 1 to block 3, controlled for by the change in repetition suppression between self and familiar other over the same blocks” p. 422).

Anyway, long story short, the behavioral results showed that the subjects tended to alter their preferences to match their partner’s (although not told to do so, it had no impact on their own money gain, there were not time constraints, and sometimes were told that the “partner” was a computer).

These behavioral changes were matched by the changes in the activation pattern of the medial prefrontal cortex (mPFC), in the sense that learning of the preferences of another, which you can imagine as a specific neural pattern in your brain, changes the way your own preferences are encoded in the same neural pattern.

Reference: Garvert MM, Moutoussis M, Kurth-Nelson Z, Behrens TE, & Dolan RJ (21 January 2015). Learning-induced plasticity in medial prefrontal cortex predicts preference malleability. Neuron, 85(2):418-28. doi: 10.1016/j.neuron.2014.12.033. Article + FREE PDF

By Neuronicus, 11 October 2015