Parental brain
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/BLW_Maternal_Affection.jpg/220px-BLW_Maternal_Affection.jpg)
Parental experience, as well as changing hormone levels during pregnancy and postpartum, cause changes in the parental brain.[1] 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.[2] Research has shown that hormones such as oxytocin, prolactin, estradiol and progesterone are essential for the onset and the maintenance of maternal behavior in rats, and other mammals as well.[3][4][5][6][7][8] Mothering behavior has also been classified within the basic drives (sexual desire, hunger and thirst, fear, power/dominance etc.).[9]
Less is known about the paternal brain, but changes in the father's brain occur alongside the mother. [1] Research on this topic is continuing to expand as more researchers examine fathers. Many of the brain regions and networks responsible for parental behavior are responsible for parental behavior in human fathers after having a child.[10] Changes in hormones, brain activation and brain structure (mainly changes in gray matter) are seen in both human mothers and fathers, with hormonal changes beginning in both males and females before the birth of their children, with changes continuing to develop after the birth of children.[11]
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.
Oxytocin
The levels of oxytocin in the maternal brain correlate with maternal behaviors such as gazing, vocalization, positive affect, affectionate touch and other similar mother-infant relationship behaviors.[12]
Estradiol and progesterone
High mother-infant attachment correlates with a higher ratio of estradiol/progesterone at the end of pregnancy, than at the beginning.[12]
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.[14][15] Mothers with high levels of cortisol were also found to be more vocal towards their children.[14][15] Mothers who experienced adversity in their own childhood, had higher daily patterns of cortisol levels, and were less maternally sensitive.[16]
Glucocorticoids
Glucocorticoids are not essential for displaying maternal behaviors, but in mothers, the levels of glucocorticoids are elevated as to initiate lactation.[17][18]
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.[2]
The
- mother's affect (changes made by the amygdala, prefrontal cortex)
- stimulus salience (changes made by the amygdala and nucleus accumbens)
- attention (changes made by the medial prefrontal cortex)
- memory (changes made by the medial prefrontal cortex).
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/03/Natalie_after_breastfeeding.jpg/220px-Natalie_after_breastfeeding.jpg)
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.[19] Increased activity has also been observed in the amygdala as the mother is responding to emotions seen in negative (fearful) faces,[21] positive faces[22][23][24] or familiar faces[25] that her baby makes. Primate mothers with damage to the prefrontal cortex have also been associated with disrupted maternal behavior.[26]
The dorsolateral prefrontal cortex (DLPFC) plays a role in the attention, cognitive flexibility and working memory of the mother.[2] 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.[2]
The
Postpartum changes
Changes in
In animal mothers
Postpartum, new neuron production is suppressed due to decreased levels of
In animals, structures of the mother's brain change
The volume of gray matter increases postpartum in the following brain regions:[33]
- bilateral hypothalamus
- amygdala
- substantia nigra
- globus pallidus.
These changes in the brain may occur in order to promote appropriate mothering behavior.[33] 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.[33]
Also in rats, the increased interaction with pups causes an increase in density in the
Postpartum, the substantia nigra activates positive responses to the pup stimuli via dopamine neurons.[33]
In human mothers
The
In human mothers there was a correlation between increased gray matter volume in the substantia nigra and positive emotional feelings towards the infant.[36][37]
Other changes such as
Maternal experience alters behaviors which stem from the hippocampus such as enhancing spatial navigation learning and behaviors linked with anxiety.[29]
Recent research has begun to look at how maternal psychopathology affects the maternal brain in relation to parenting.
Early experiences and shaping
Women who had a positive experience involving their family in their childhood are more likely to be more
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.
Larger gray matter and increased activations of the following brain areas occur in mothers who had experienced higher quality maternal care as infants:[55]
- middle temporal gyrus
- superior temporal sulcus and
- middle frontal cortex.
This allows the mother to be more sensitive to her own infant's needs.[55]
Postpartum depression has also been associated with mothers who received low quality maternal care early in their own life.[56]
Paternal brain
In only 6% of
Paternal hormonal effect
An increase in levels of
In animal fathers
In father rats, just as in the mother rats, a decrease in
Marmoset fathers have enhanced dendritic spine density in the prefrontal cortex. This increase correlates with increase in vasopressin 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.[1][63]
Changes in neurogenesis in the prefrontal cortex of the paternal brain have been linked in some species to recognition of kin.[64]
In human fathers
Being exposed to crying babies activates the prefrontal cortex and the amygdala in both fathers and mothers, but not in non-parents.[65][66] The level of testosterone in the paternal brain correlates with the effectiveness of the father's response to the baby's cry.[61] Increased levels of prolactin in the paternal brain has also been correlated with a more positive response to the infant's cry.[61] Similar to mothers, fathers have a reduction of gray matter in the orbitofrontal cortex areas, and increase of gray matter in the hypothalamus and amygdala after having a child.[67][11]
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- ^ Insel, T (1990). Oxytocin and maternal behavior, Mammalian parenting: biochemical, neurobiological and behavioral determinants. New York: Oxford University Press. pp. 260–280.
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