Children who are more emotionally sensitive may be more responsive to both supportive and adverse caregiving experiences as measured in the amygdala, a brain region involved in responding to stress and regulating emotions.
The results, which combined data from two independent studies, were outlined in a paper published May 5 in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. The research focused on the amygdalar activity of roughly 12,000 youths. The new findings add more nuance to researchers' understanding of how environmental and biological factors interact to shape human psychology — especially in childhood, when one's brain may be particularly sensitive to one's surroundings.
"We tend to divide nature and nurture — biology and environment — as two entities," Assaf Oshri, a developmental psychologist at the University of Georgia and the senior author on the paper, told The Academic Times. Yet "even the same type of parenting — the same style with the same parents — can influence individuals very, very differently depending on their biology."
The researchers think amygdalar activity could one day be used as a biomarker to identify people who may be at risk of experiencing social or psychological issues as a result of growing up in damaging caregiving environments. But Oshri cautioned that it is too early to establish a causal relationship between parenting styles and amygdalar activity alone; other regions of the brain likely play a role in shaping these associations, too.
The researchers' first study utilized data from 11,875 youth. The information was already available thanks to the Adolescent Brain Cognitive Development Study, a longitudinal, long-term evaluation of childhood brain development.
Oshri and his colleagues found that children whose left amygdalae are more sensitive to positive stimuli — measured by performing a memory test with happy, fearful and neutral faces — showed more significant benefits from growing up with warm parenting styles, or those that include lots of support, praise and displayed affection.
Researchers assessed parental warmth by asking questions such as how much a parent comforts a child after he or she discusses a worrying situation or the degree to which a parent enjoys engaging in activities with their child. The benefits of parental warmth were measured by assessing children's prosociality — the degree of altruism and cooperation they exhibited. Meanwhile, children with high sensitivity who experienced low parental warmth showed lower levels of prosociality.
A second study, based on locally sourced data, used a sample of 123 youth from rural Georgian families. Its evaluation of family functioning included measures of rigidity and chaos as well as enmeshment — the extent that family relationships may cross healthy boundaries. All of these factors contribute to the balance of one's rearing environment.
The results complemented the findings of the first study. Higher reactivity in both the right amygdala and the left amygdala correlated with fewer internalizing issues — such as depression and anxiety — for those who lived in a healthy, balanced family environment. The opposite was also true: Children with reactive amygdalae who experienced an unbalanced family life showed higher levels of internalization. And both studies indicated that youth who showed less sensitivity to positive or negative stimuli were less likely to be influenced by their parents' or caregivers' rearing styles.
But not all of the negative neurological effects of unbalanced parenting styles are set in stone, since childrens' brains are capable of rewiring themselves over time depending on environmental conditions.
"This neural plasticity enables youths with the potential to reprogram their neural functions to be consistent with current experiences," the authors wrote.
The amygdala is part of the salience network — the system that humans use to evaluate which stimuli in the environment are worth our time and attention. Yet, scientists haven't fully determined the amygdala's functions. Some evidence suggests that heightened activation of the amygdala during exposure to negative stimuli could be related to long-term negative mood. Scientists are also working to understand how children's prior exposure to violence, including spanking, could influence activity in the amygdala.
But the question isn't as simple as: "Is [the amygdala] working well or not?" Oshri said. "It can work the same way for kids and lead to very bad, negative developmental outcomes."
"Or it can lead to very positive results — a Nobel Prize winner — with the same biology," he added.
For now, the evidence suggests that, although some biological factors may be immutable, the environment can be more easily changed in order to meet the needs of kids, according to Oshri.
"We have a lot of responsibilities," he said. [We] represent the environment as parents or communities to influence the development of children."
The study "Amygdalar activation as a neurobiological marker of differential sensitivity in the effects of family rearing experiences on socioemotional adjustment in youths" published May 5 in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, was authored by Sihong Liu, University of Oregon; and Assaf Oshri, Steven M. Kogan, K.A.S. Wickrama and Lawrence Sweet, University of Georgia.