The New-born Brain and Differences in Sensitivity to Parenting

Background information

There is ample amount of research showing that children vary in their sensitivity to parenting quality (1, 2) (see also the blog post by Dr F. Lionetti: Parenting Quality and Sensitive Children). For example, more sensitive children exposed to more supportive parenting, such as positive parenting practices and higher parental sensitivity to child’s needs, show higher social competence whereas those exposed to parenting practices of lower quality, such as harsh and negative parenting, may show increased internalizing and behaviour problems later in development.

Parenting quality is also related to the development of cognitive functions (3). Especially higher-order cognitive functions, called executive functions, are of interest since they develop rapidly in early childhood and have relevance for many domains of life such as academic performance, everyday functioning, and social-emotional outcomes. The influence of parenting quality on child cognitive outcomes is likely to vary in children with different degrees of sensitivity.

Recently, research has aimed at understanding which characteristics of the brain are associated with the degree of individual sensitivity to the environment. It is suggested that brain areas related to social-emotional processing and attention (i.e. salience network; anterior cingulate) and stress regulation (hippocampus, amygdala) may contribute to sensitivity (4).

Interestingly, total brain size has been regularly linked with cognitive outcomes, but its role regarding an individual’s sensitivity to the environment has not been studied. Overall, we know very little about the characteristics underlying sensitivity in young infants.

In our study, we tested whether children with certain brain characteristic at birth (i.e. larger overall brain size, hippocampus and anterior cingulate) perform better in cognitive tasks in toddlerhood and preschool age, if exposed to high parenting quality in infancy (5). In turn, we expected that children with similar brain features would show poorer cognitive function if exposed to low quality parenting.

How was the study conducted?

We studied 53 mother-child pairs who participated in a longitudinal cohort study at the University of California Irvine. The new-borns’ brains were scanned using Magnetic Resonance Imaging (MR) approximately 3-4 weeks after birth.

Parenting quality of the mother was observed in a mother-infant free-play situation when the child was 6 months of age. Child cognitive and executive functioning was assessed at 2 and 5 years of age using six standardized tasks that measure various aspects of cognitive development (e.g., ability to memorize the location of a sticker in a moving rotating tray).

What did we find?

Overall, compared to their peers with smaller brain size, new-borns with larger brain size were indeed more sensitive to parenting quality in terms of cognitive performance.

More specifically, children with larger brain size showed better performance in 4 out of 6 tasks, if the quality of the parenting they received high. In contrast, children with similar brain characteristics but who were exposed to lower parenting quality showed poorer performance (see Figure 1 below for an example).

Furthermore, larger new-born hippocampus volume (i.e. brain structure related to stress regulation and cognition) was associated with better task performance at 2 years of age in the context of high parenting quality but worse task performance in the context of low parenting quality. Larger new-born anterior cingulate volume (i.e. structure related to executive attention and social processing) increased child sensitivity to parenting quality in terms of cognitive performance at 5 years.

What does this all mean?

To conclude, brain structural features at birth may represent a marker of infants’ sensitivity to their social-emotional environment. In turn, infants’ degree of sensitivity indicates the extent to which cognitive outcomes may be affected by the quality of the early rearing environment.

So, having larger brain volume at birth overall and in the areas relevant for social processing, attention, and stress regulation may reflect higher plasticity in these brain regions (large volumes could reflect more neurons and axons). This plasticity then increases the capacity to benefit from high quality environments.

What is especially novel in this study is the fact that features of the newborn brain are related to Differential Sensitivity to the environment. In fact, the studied neural features cannot yet have been shaped by postnatal (e.g., parenting) experiences. Therefore, the interindividual variation we observe at the time of birth is the product of genetic and prenatal environmental factors.

The findings also propose that many brain areas that are thought to affect social-emotional development and cognition, are also associated with individual sensitivity. Thus, the “neuroscience of sensitivity” will help us to understand which specific cognitive and emotional functions underlie sensitivity.

Furthermore, studying neural structure and function may increase our understanding of whether sensitivity can be increased over time, or whether it is a fixed trait.

Prenatal stress, for instance, may affect brain characteristics that then affect sensitivity (see blog post by Dr S. Hartman: Prenatal Stress Promotes the Development of Sensitivity). This suggests that the way we respond to the environment is a consequence of previous experiences that impact the brain and its function, which in turn then influences the way we perceive and respond to experiences.

However, we need more information about the exact mechanisms that explain these associations. Considerably larger sample sizes are also needed in future to understand the highly sensitive brain.

Our future studies will continue to test which brain structural and functional characteristics are linked with both individual sensitivity and early life stress exposures to address these questions.