Bengaluru Sep 16, 2019, (Research Matters):
A two-year-old child looks at the four colourful squares blinking on the displays in front of her. The squares on the left side are blue and orange, and on the right, they are red and green. She looks at them for half a second before the screen goes blank for a while, and the squares reappear. Only this time, the red square on the right has changed to purple, drawing the child's attention. When the same experiment is conducted on another two-year-old, she cannot detect this change at all. Why?
Of course, the difference in responses points to how the brain functions—how it remembers its surroundings and detects changes. But there is more. This difference could also indicate inequality in the two children's parents education level, and their economic status says a new study. The study, published in the journal Developmental Science, looks into how children from disadvantaged backgrounds perceive visual changes. The researchers were from the University of Stirling, UK, University of East Anglia, UK and the Community Empowerment Lab in Uttar Pradesh, India.
Every year, 250 million children or a whopping 43% of children below the age of 5 are at risk of not reaching their biological and physiological potential in low and middle-income countries, like India. The primary reason for this is poverty, where the acute lack of resources can stunt the child's brain development even before she is born. During childhood, she is also more likely to suffer learning disabilities leading to the lower future income, thereby propagating the vicious cycle of poverty. If we could then measure the impact of poverty on brain development, it can help us identify those who need help. It can also evaluate how well our interventions are working.
Previous studies have used Magnetic Resonance Imaging (MRI) technique to create pictures of the brain using magnetic fields. These pictures have shown that children from lower socio-economic backgrounds have reduced white and grey matter in the brain, essential for information processing. However, very few studies have looked at what exact function might differ. In this study, the researchers have studied the Visual Working Memory (VWM) function in 34 children between the ages of 4 to 48 months in Shivgarh, rural Uttar Pradesh.
The visual working memory acts like a sticky note in the brain. It briefly remembers the surroundings and helps to detect any small changes. Information stored here can either be forgotten or retained for future use. The visual working memory starts developing in early infancy and improves throughout childhood. Given how crucial VWM is for tasks such as learning, it can predict how well the child performs in academics later in life. Most studies rely on functional MRI (fMRI) to assess this function of the brain. However, this technique is expensive and requires the child to stay still in a dark and noisy environment.
In the current study, the researchers instead use a cost-effective and portable technique called Function Near-Infrared Spectroscopy (fNIRS). Here, the child wears a cap with lights focused on the scalp, which is then absorbed by the brain tissue. Detectors then measure the light that bounces back, which tell us what parts of the brain are activated during a specific task. They monitored the brain regions while the children performed a simple task that engaged the Visual Working Memory. They were tested if they could observe the changes in the colours of the square and remember them. If the child did not look at the display, then her VWM was not engaged.
The analysis showed that children belonging to a higher socio-economic background could better detect changes than those from a lower socio-economic background. The brain scan also showed that these children showed little activity in several regions of the brain like the frontal cortex. This observation suggests that the brain could suppress distracting and irrelevant information. For children that were not able to detect any change, this region was active, implying that they might have trouble disengaging from visual displays when they need to.
The study also found that the activities in the dorsolateral prefrontal cortex and the inferior frontal gyrus aided change detection. Their activation was strongly associated with the education level of the mother and higher household-income, respectively. The researchers are currently examining how Indian mothers with different educational backgrounds interact with children and impact their performance in the task. Children raised in higher income-households have better opportunities to develop cognitive abilities as they can afford to have a diverse learning environment.
Since the VWM task was adapted from studies done in Western countries, the researchers further explored if these were appropriate in the Indian context. They compared the brain scan results from the Indian sample to those from the US and found that the regions of activation and suppression largely overlapped.
The study is a first-of-its-kind in India to show that a portable and cost-effective neuroimaging technology can be used to assess a simple behavioural task in a rural setting. As a next step, the researchers aim to study more children across different age groups to understand the impact of early adversity on behaviour and function of the brain from specific socio-economic backgrounds.
"This could have far-reaching implications, bringing cutting edge technology to the settings in which it is most severely needed," they conclude.