June 28, 2013
Researchers Take A Look Inside The Mind Of A Child
April Flowers for redOrbit.com - Your Universe Online
There is an intense look of concentration that is nearly universal to young children when their minds are hard at work. Despite recognizing the look, however, adults are never really sure what the children are thinking.
A new study, led by psychologists at the University of Iowa, has used optical neuroimaging to peer inside the brain, in a first-ever attempt to quantify how much 3- and 4-year-old children are grasping when they survey their surroundings, and what regions of the brain are in play. The study, published in the journal NeuroImage, examined "visual working memory," a core cognitive function in which we stitch together what we see at any given point in time to help focus attention.
By using a series of object-matching tests, the researchers found 3-year-olds can hold a maximum of 1.3 objects in visual working memory, while 4-year-olds reach capacity at 1.8 objects. Prior studies have shown that adults max out at approximately 3 to 4 objects.
"This is literally the first look into a 3- and 4-year-old's brain in action in this particular working memory task," says John Spencer, psychology professor at the UI.
The implications of these findings are important. Visual working memory performance has been linked to a variety of childhood disorders, including attention-deficit/hyperactivity disorder (ADHD), autism and developmental coordination disorder, as well as affecting children born prematurely. The team's goal is to apply the new brain imaging technique to detect these disorders before they manifest themselves in children's behavior.
"At a young age, children may behave the same," notes Spencer, who's also affiliated with the Delta Center, "but if you can distinguish these problems in the brain, then it's possible to intervene early and get children on a more standard trajectory."
There has been a wealth of research into visual working memory in children and adults, which divined neural networks in action using function magnetic resonance imaging (fMRI). This approach worked well with adults, but not so much with children. Children, especially young ones, throw off the machine's readings with jerky movements. The UI team turned to functional near-infrared spectroscopy (fNIRS). The technique has been around since the 1960s, but has never been used to look at working memory in children as young as three years of age.
"It's not a scary environment," says Spencer of the fNIRS. "No tube, no loud noises. You just have to wear a cap."
Similar to the way fMRI works, fNIRS records neural activity by measuring the difference in oxygenated blood concentrations anywhere in the brain. When a region of the brain is activated, neurons fire like crazy, eating up the oxygen supply in the blood. Another shipment of oxygen-rich blood is necessary to keep the neurons going. Measuring the contrast between oxygen-rich and oxygen-deprived blood allows the researchers to know which area of the brain is going full tilt at the time.
The children were outfitted with colorful, comfortable ski hats woven with optic wires. The children then played a computer game. They were shown a card with one to three objects of different shapes for two seconds. Then they were shown a second card after a one second pause that had either the same or different shapes. The children reported whether they had seen a match or not.
The results were surprising. First, the researchers observed neural activity in the right frontal cortex was an important barometer of higher visual working memory capacity in both age groups. Understanding this could help doctors evaluate visual working memory at a younger age than before and work with children whose capacity falls below the norm.
The second finding revealed that 4-year-olds showed a greater use than 3-year-olds of the parietal cortex, located in both hemispheres below the crown of the head and which is believed to guide spatial attention.
"This suggests that improvements in performance are accompanied by increases in the neural response," adds Aaron Buss, a UI graduate student in psychology. "Further work will be needed to explain exactly how the neural response increases--either through changes in local tuning, or through changes in long range connectivity, or some combination."