Parental experience, as well as changing hormone levels during pregnancy and postpartum, cause changes in the parental brain. Displaying maternal sensitivity towards infant cues, processing those cues and being motivated to engage socially with her infant and attend to the infant's needs in any context could be described as mothering behavior and is regulated by many systems in the maternal brain. Research has shown that hormones such as

oxytocin Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin ...

prolactin Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...

estradiol Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development of f ...

and

progesterone Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the m ...

are essential for the onset and the maintenance of maternal behavior in rats, and other mammals as well. Mothering behavior has also been classified within the basic drives (sexual desire, hunger and thirst, fear, power/dominance etc.). Less is known about the paternal brain, but changes in the father's brain occur alongside the mother once the offspring is born.

Maternal brain

Maternal hormonal effect

Different hormone levels in the maternal brain and the overall well being of the mother account for 40%–50% of differences in the mother's attachment to her infant. Mothers experience a decrease in

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...

and an increase in

and

caused by

lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The proces ...

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

parturition Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...

and interaction with the infant.

Oxytocin

The levels of

in the maternal brain correlate with maternal behaviors such as gazing, vocalization, positive affect, affectionate touch and other similar mother-infant relationship behaviors.

Estradiol and progesterone

High mother-infant attachment correlates with a higher ratio of

at the end of

, than at the beginning.

Cortisol

In the first few days after giving birth the levels of cortisol are high which correlates with maternal approach behavior and positive maternal attitudes. Mothers with high levels of cortisol were also found to be more vocal towards their children. Mothers who experienced adversity in their own childhood, had higher daily patterns of

cortisol Cortisol is a steroid hormone, in the glucocorticoid class of hormones. When used as a medication, it is known as hydrocortisone. It is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in the adrenal gland ...

levels, and were less maternally sensitive.

Glucocorticoids

Glucocorticoids are not essential for displaying maternal behaviors, but in mothers, the levels of glucocorticoids are elevated as to initiate lactation.

Neuroanatomy

Different areas/structures of the brain are associated with different factors which contribute to maternal behavior. One's own infant acts as a special stimulus which triggers activation of different areas of the brain. These brain areas together allow for maternal behavior and related systems. The Medial Preoptic Area (MPOA) of the hypothalamus contains receptors for

vasopressin Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...

and

opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid us ...

s. All these hormones are involved in some way in activating maternal behavior in the brain. The following are other behavioral changes necessary for mothering that the MPOA is responsible for: * mother's affect (changes made by the

amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verteb ...

prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...

) * stimulus salience (changes made by the

and

nucleus accumbens The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...

) * attention (changes made by the

and

medial prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...

) * memory (changes made by the

and

The amygdala and medial prefrontal cortex also contain receptors for the hormones which are most likely to be changing behavior at the time of pregnancy, and may be the sites where these changes occur. Increased activity has also been observed in the amygdala as the mother is responding to emotions seen in negative (fearful) faces, positive faces or familiar faces that her baby makes. Primate mothers with damage to the

have also been associated with disrupted maternal behavior. The

dorsolateral prefrontal cortex The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the primate brain. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adultho ...

(DLPFC) plays a role in the attention, cognitive flexibility and working memory of the mother. It helps the mother identify infant cues. In any environment and efficiently, it allows for the decision-making and action planning process involved in attending to the infant's cues. The

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

parietal cortex The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory inform ...

, and

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...

serve for processing the smell, touch and vocalization associated with the infant.

Postpartum changes

Changes in

and

in the early

postpartum The postpartum (or postnatal) period begins after childbirth and is typically considered to end within 6 weeks as the mother's body, including hormone levels and uterus size, returns to a non-pregnant state. The terms puerperium, puerperal pe ...

period cause changes in the structures of the maternal brain.

In animal mothers

Postpartum, new neuron production is suppressed due to decreased levels of

and increased levels of

glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...

mother rats. Mother-infant interaction is also thought to suppress

neurogenesis Neurogenesis is the process by which nervous system cells, the neurons, are produced by neural stem cells (NSCs). It occurs in all species of animals except the porifera (sponges) and placozoans. Types of NSCs include neuroepithelial cells (NECs) ...

in the

hippocampus The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, a ...

postpartum in the rat maternal brain. Maternal experience increases

in the

subventricular zone The subventricular zone (SVZ) is a region situated on the outside wall of each lateral ventricle of the vertebrate brain. It is present in both the embryonic and adult brain. In embryonic life, the SVZ refers to a secondary proliferative zone ...

(SBZ) which is responsible for producing the neurons of the

olfactory bulb The olfactory bulb (Latin: ''bulbus olfactorius'') is a grey matter, neural structure of the vertebrate forebrain involved in olfaction, the sense of odor, smell. It sends olfactory information to be further processed in the amygdala, the orbitof ...

Prolactin Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...

is the hormone which mediates the increase in

in SBZ. In animals, structures of the mother's brain change

due to the increased interaction of the mother with the infant. The volume of gray matter increases postpartum in the following brain regions: * bilateral

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...

substantia nigra The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. ''Substantia nigra'' is Latin for "black substance", reflecting the fact that parts of the substantia nigra app ...

globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one internal, known in rod ...

. These changes in the brain may occur in order to promote appropriate mothering behavior. The mother's positive attitude towards the infant can be used as a predictor for the increase in gray matter in the above stated brain structures. Also in rats, the increased interaction with pups causes an increase in density in the MPOA. Postpartum increase in gray matter volumes may help the mother activate the motivation to perform maternal behavior in response to cue from their offspring. Postpartum, the

activates positive responses to the pup stimuli via

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...

neurons.

In human mothers

The amygadala,

and

begin to change during pregnancy due to the high levels of

stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...

experienced by the mother during this time. In human mothers there was a correlation between increased gray matter volume in the

and positive emotional feelings towards the infant. Other changes such as

menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs a ...

hydration Hydration may refer to: * Hydrate, a substance that contains water * Hydration enthalpy, energy released through hydrating a substance * Hydration reaction, a chemical addition reaction where a hydroxyl group and proton are added to a compound * ...

weight In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a Euclidean vector, vector quantity, the gravitational force acting on the object. Others define weigh ...

and

nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient n ...

may also be factors which trigger the maternal brain to change during

and

. Maternal experience alters behaviors which stem from the

such as enhancing spatial navigation learning and behaviors linked with

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...

. Recent research has begun to look at how maternal psychopathology affects the maternal brain in relation to parenting.

Daniel Schechter Daniel S. Schechter (born 1962 in Miami, Florida) is an American psychiatrist known for his clinical work and research on intergenerational transmission or "communication" of violent trauma and related psychopathology involving parents and very ...

and colleagues have studied specifically interpersonal violence-related

posttraumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on ...

(PTSD) and comorbid

dissociation Dissociation, in the wide sense of the word, is an act of disuniting or separating a complex object into parts. Dissociation may also refer to: * Dissociation (chemistry), general process in which molecules or ionic compounds (complexes, or salts ...

as associated with specific patterns of maternal neural activation in response to viewing silent video-stimuli of stressful parent-toddler interactions such as separation versus less-stressful ones such as play. Importantly, less medial

activity and greater

limbic system The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ''Ps ...

activity (i.e.

entorhinal cortex The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe, whose functions include being a widespread network hub for memory, navigation, and the perception of time.Integrating time from experience in the ...

and

) were found among these post-traumatically stressed mothers of toddlers compared to mothers of toddlers without PTSD in response to stressful parent-child interactions as well as, within a different sample, in response to menacing adult male-female interactions. In the latter study, this pattern of corticolimbic dysregulation was linked to less observed maternal sensitivity during mother-child play. Decreased ventral-medial prefrontal cortex activity in violence-exposed mothers, in response to viewing their own and unfamiliar toddlers in video-clips of separation versus play, has also been associated with increased PTSD symptoms,

parenting stress Parenting stress relates to stressors that are a function of being in and executing the parenting role. It is a construct that relates to both psychological phenomena and to the human body's physiological state as a parent or caretaker of a child. ...

and decreased methylation of the glucocorticoid receptor gene.

Early experiences and shaping

Women who had a positive experience involving their family in their childhood are more likely to be more maternally sensitive and provide that same experience for their own children. Mothers that had negative experiences involving their families undergo neurobiological changes which lead to high

reactivity and

insecure attachment Attachment theory is a psychological, evolutionary and ethological theory concerning relationships between humans. The most important tenet is that young children need to develop a relationship with at least one primary caregiver for normal ...

. This causes lower maternal responsiveness to their infant's needs. Rat mothers provide high levels of maternal care (licking and grooming) to their offspring if they themselves received high maternal care as a pup from their own mothers. Rat mothers who received low levels of maternal care as pups have lower levels of expression of the

glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...

receptor gene and lower synaptic density in the

. In human mothers, lower hippocampal volume has been associated with a lower ability to regulate emotions and stress, which can be linked with decreased maternal sensitivity as a mother. Mothers with

s to their own mothers display higher amygdala sensitivity to negative emotional stimuli, like hearing their infant cry. Having more difficulty dealing with stress makes mothers less responsive to their infant's cues. Larger gray matter and increased activations of the following brain areas occur in mothers who had experienced higher quality maternal care as infants: * middle temporal

gyrus In neuroanatomy, a gyrus (pl. gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; sg. ''sulcus''). Gyri and sulci create the folded appearance of the brain in humans and other ma ...

superior temporal sulcus The superior temporal sulcus (STS) is the sulcus separating the superior temporal gyrus from the middle temporal gyrus in the temporal lobe of the brain. A sulcus (plural sulci) is a deep groove that curves into the largest part of the brain, ...

and * middle frontal cortex. This allows the mother to be more sensitive to her own infant's needs.

Postpartum depression Postpartum depression (PPD), also called postnatal depression, is a type of mood disorder associated with childbirth, which can affect both sexes. Symptoms may include extreme sadness, low energy, anxiety, crying episodes, irritability, and chan ...

has also been associated with mothers who received low quality maternal care early in their own life.

Paternal brain

In only 6% of

mammalian Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...

species, including humans, the father plays a significant role in caring for his young. Similar to the changes that occur in the maternal brain, the same areas of the brain (

etc.) are activated in the father, and hormonal changes occur in the paternal brain to ensure display of parenting behavior.

Paternal hormonal effect

An increase in levels of

and

occur in the paternal brain. These hormonal changes occur through the father's interaction with the mother and his offspring.

Oxytocin Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin ...

levels are positively correlated with the amount of affection the father displays towards the child. In humans, and in other primate species, lower levels of

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...

have been linked to the display of paternal behavior.

In animal fathers

In father rats, just as in the mother rats, a decrease in

in the

occurs

. Just like in mothers, fathers also have increased levels of

which are thought to suppress the production of new cells in the brain.

Marmoset The marmosets (), also known as zaris or sagoin, are 22 New World monkey species of the genera ''Callithrix'', ''Cebuella'', ''Callibella'', and ''Mico''. All four genera are part of the biological family Callitrichidae. The term "marmoset" is ...

fathers have enhanced dendritic spine density in the

. This increase correlates with increase in

receptors in this area of the paternal brain. With age, this effect is reversed, and is therefore believed to be driven by father-infant interactions. Changes in

in the

of the paternal brain have been linked in some species to recognition of kin.

In human fathers

Being exposed to crying babies activates the

and the

in both fathers and mothers, but not in non-parents. The level of

in the paternal brain correlates with the effectiveness of the father's response to the baby's cry. Increased levels of

in the paternal brain has also been correlated with a more positive response to the infant's cry.

References

{{reflist, colwidth=30em Parenting Brain Developmental neuroscience Neuroendocrinology