The science of “mommy brain”: How dopamine locks in lifelong cognitive benefits for mothers

A recent study published in the journal Nature suggests that the biological transition to motherhood creates lifelong molecular changes in the brain driven by the neurotransmitter dopamine. The research provides evidence that these lasting modifications improve learning and memory, while also showing that chronic stress after birth can disrupt this natural neurological adaptation.

The motivation for the research stemmed from a broader interest in neuroplasticity, which is the brain’s ability to adapt to environments over time. “Our lab is broadly interested in how experiences leave lasting changes in the brain,” said Ian Maze, a professor at the Icahn School of Medicine at Mount Sinai and a Howard Hughes Medical Institute investigator, and Jennifer O’Chan, an instructor at the Icahn School of Medicine at Mount Sinai. In a joint statement, the authors explained the origin of their study.

“We know, for example, that stress early in life can have long-lasting effects on behavior and brain function,” the researchers noted. “But stress comes in many forms, social, psychological, environmental, and physiological.” Because environmental factors heavily influence brain plasticity, they wanted to examine one of life’s biggest transitions.

“And pregnancy and postpartum represent some of the most profound physiological stressors and biological changes a person can go through,” the authors added. “So we wanted to ask: do these experiences leave a lasting imprint on the brain?” The process of becoming a mother involves immense physical and emotional transformations to support pregnancy, childbirth, and newborn care.

Previous imaging studies in humans have indicated that carrying a pregnancy to term alters brain structure and connectivity for many years. Animal models also display enduring changes in brain cell connections and behavior following reproductive events. Despite this knowledge, the exact molecular processes that lock in these long-lasting neurological changes remain mostly unknown.

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Because maternal behaviors rely on a complex network of hormones and brain chemicals, the authors wanted to map how gene expression changes across different brain regions. Gene expression refers to the way our cells turn specific instructions encoded in our DNA into functional products like proteins. By tracking which genes are turned on or off after the reproductive period ends, the scientists hoped to isolate the primary chemical pathways responsible for lasting maternal adaptations.

The researchers started by comparing adult female mice that had experienced breeding, pregnancy, birth, and nursing to female mice of the same age that had never been pregnant. They waited until four weeks after the mouse pups had been weaned to ensure that acute pregnancy hormones had returned to baseline levels. They then extracted tissue from eleven different brain regions known to be involved in maternal behavior.

Using a technique called RNA sequencing, which reads the genetic messages active in a cell at a given time, they quantified how many genes had altered their activity levels. They found that a region called the dorsal hippocampus showed the highest number of altered genes. The hippocampus is a brain structure primarily responsible for spatial navigation and forming new memories.

To test if these genetic changes affected actual behavior, the authors observed the mice in a pup retrieval task and a fear conditioning test. The mothers retrieved scattered newborn pups significantly faster than the non-mothers. In the fear conditioning test, the mothers displayed enhanced learning and stronger memory recall of an environment associated with a mild foot shock compared to the females that had never been pregnant.

Next, the authors set out to determine which specific reproductive events drove these lasting memory and gene alterations. They compared several groups of female mice, including those that mated but did not get pregnant, those that gave birth but had their pups removed immediately, and virgins that spent twenty-one days interacting with foster pups. By analyzing the hippocampus of these different groups, the researchers noted that pregnancy itself provided the strongest genetic shift.

The combination of mating, pregnancy, and birth closely mirrored the gene expression profile of a full reproductive experience, though it lacked the full magnitude. This suggests that the complete sequence of maternal events, including postpartum newborn care, is necessary to fully cement the long-term changes in the brain. The scientists concluded that the postpartum period acts as a sensitive window to reinforce these new neurological pathways.

To see what happens when this sensitive window is disrupted, the scientists introduced a chronic stress model during the nursing phase. This part of the methodology came about unexpectedly. “There were several very exciting and unexpected findings!” the authors said. “One of the most important, we collaborated with early life adversity investigators who were not utilizing the dams from their litters to identify the effects of postpartum stress.”

“This was a serendipitous collaboration and led to the observation that postpartum stress disrupted the effects of parity on the maternal brain,” they explained. “This ended up being very important for our study, as the postpartum stress group provided a defined window where we could observe how dopamine levels were changing in response to pup separation, relative to control dams.”

“This provided the insight needed to conduct follow up experiments examining dopamine and histone dopaminylation contributions to the maternal brain,” the authors noted.

Between ten and twenty days after giving birth, a group of eleven mothers was separated from their litters for three hours each day and given limited nesting materials. Following the weaning period, the researchers tested this stressed group alongside twelve unstressed mothers and eleven females that had never been pregnant.

The stressed mothers failed to show the enhanced memory and learning responses during the fear conditioning tasks. When looking at the genetic profiles in the hippocampus, the stressed mothers clustered somewhere between the non-mothers and the unstressed mothers. The stress experienced during the nursing phase seemed to block the natural genetic remodeling that normally accompanies motherhood.

The authors then used a highly precise method called single-cell RNA sequencing to look at individual cells within the hippocampus. They analyzed over one hundred thousand individual cell nuclei across the different mouse groups to see which specific cell types were changing. They found that neurons producing specific receptors for dopamine were significantly altered in the unstressed mothers.

Dopamine is a chemical messenger in the brain typically associated with reward, motivation, and learning. By measuring dopamine levels during the pup separation stress test, the researchers observed that acute separation caused a spike in dopamine in the hippocampus. Chronic separation stress elevated the baseline dopamine levels persistently.

This indicates that the normal transition to motherhood relies on a precise balance of dopamine signaling. Disrupting this balance through stress prevents the brain from solidifying its adaptive maternal changes. To understand how dopamine alters gene expression so permanently, the scientists examined a process called histone dopaminylation.

Histones are protein spools around which long strands of DNA are wound, helping to package the genetic code neatly inside a cell. When a chemical tag like dopamine attaches to these histone proteins, it can loosen or tighten the DNA winding, changing how easily genes can be read and activated. This type of environmentally driven change to DNA packaging is known as epigenetics.

The researchers mapped these dopamine tags across the genetic material in the hippocampus of four mice per group. They found that healthy mothers had fewer of these dopamine tags near specific genes compared to non-mothers and stressed mothers. To confirm these findings apply outside of animal models, the scientists examined postmortem human brain tissue.

They analyzed samples from three women who had never given birth and five women who had given birth one or two times. The human tissue from the mothers showed similar patterns of altered gene expression and reduced histone dopaminylation in the hippocampus. This provides evidence that the molecular remodeling seen in mice is a shared biological feature of human motherhood.

To prove that dopamine changes actually cause the brain remodeling, the scientists used a chemical and viral tool to artificially suppress dopamine release in the hippocampus of virgin mice. Fifteen virgin mice received this dopamine suppression during a ten-day window. Suppressing dopamine in these females that had never been pregnant caused them to perform better on the pup retrieval task and the fear conditioning memory test.

Their genetic profiles also shifted to closely resemble the profiles of natural mothers. In a final experiment, the researchers injected a specialized virus into the brains of stressed mothers to artificially remove the excess dopamine tags from their histone proteins. This rescue procedure was performed on a group of nine stressed mothers.

Removing the excess epigenetic tags restored the enhanced learning and memory abilities that had been erased by the postpartum stress. The gene expression patterns in these rescued mice also returned to the healthy maternal state. These collected findings present a detailed picture of how maternal behaviors and cognitive boosts are locked into the brain.

People often assume pregnancy-related brain changes are a negative occurrence, but the authors hope the public takes away a different message from their findings. “First, that there is more to the term ‘mommy brain’, which usually refers to the idea that becoming a mother makes you forgetful or scattered,” the scientists said. “Our findings show that the maternal brain undergoes changes that promote adaptations to new challenges, suggesting that it is reorganized by these experiences to help meet the demands of parenthood.”

The researchers want to emphasize the importance of healthy environments during this transition. “The second takeaway is that these changes depend on the quality of the postpartum period,” they noted. “We found that chronic postpartum stress disrupts these maternal brain adaptations, suggesting stress reduction and support are incredibly important during this window.”

The researchers were careful to distinguish between everyday challenges and the type of adversity modeled in the study. “An important point I’d like to clarify is that the stress we modeled in mice was chronic, severe, and unpredictable,” they stated. “Some stress is normal and even a beneficial part of new parenthood, this type of stress drives learning and adaptation.”

“What our findings speak to are the unrelenting stressors that come from a lack of support, resources, or stability,” the scientists added. “We hope this research underscores just how critical the postpartum period is, and why the support new parents receive during this time truly matters for the long-term health of the maternal brain.”

While these findings provide new insights into the maternal brain, the study has some limitations, particularly regarding human applications. “In mice we can control everything, the environment, the stress, the timing, the genetics,” the authors noted. “In humans, the postpartum period is shaped by culture, socioeconomic status, relationship support, sleep deprivation, and/or prior mental health history.”

Because human environments are so diverse, modeling real-world parenting remains a challenge for scientists. “So while we can identify a mechanism in mice, understanding how that applies across the diversity of human experience is more complicated,” they explained. The exact contributions of other chemical messengers like oxytocin and estrogen also still need to be isolated.

Moving forward, the scientists hope to explore how this dopamine-driven brain remodeling interacts with genetic risk factors for postpartum mood disorders. “There are many exciting directions to follow up on!” Maze and O’Chan said. “One question is how the brain translates postpartum experiences into lasting molecular changes in the brain?”

“Another is whether postpartum stress influences maternal behavior or offspring interactions in a subsequent reproductive period, and whether similar brain adaptations occur in fathers and partners through caregiving experience,” they added. “The answers to these questions will have important implications not just for neuroscience, but for how we understand and support parents during these transformative periods.”

The study, “Dopamine drives persistent remodelling of the maternal brain,” was authored by Jennifer C. O’Chan, Giuseppina Di Salvo, Ashley M. Cunningham, Sohini Dutta, Elizabeth Brindley, Benjamin H. Weekley, Winnie Chen, Rasika R. Iyer, Ethan Wan, Cindy Zhang, Naguib Mechawar, Gustavo Turecki & Ian Maze.