A New Look Inside Children's Brains

Researchers at the University of Iowa have found that children have a limit to what they can see and remember at a given time, known as visual working memory. 

In tests, the researchers found that 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. 

Adults hit the ceiling at 3 to 4 objects. 

Credit: Sondra Cue, University of Iowa

When young children gaze intently at something or furrow their brows in concentration, you know their minds are busily at work but you're never entirely sure what they're thinking.

Now you can get an inside look. Psychologists led by the University of Iowa for the first time have peered inside the brain with optical neuroimaging to quantify how much 3- and 4-year-old children are grasping when they survey what's around them and to learn what areas of the brain are in play.

The study looks at "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.

In a series of object-matching tests, the researchers found that 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. By comparison, adults max out at 3 to 4 objects, according to prior studies.

"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 and corresponding author of the paper, which appears in the journal NeuroImage.

The research is important, because visual working memory performance has been linked to a variety of childhood disorders, including attention-deficit/hyperactivity disorder (ADHD), autism, developmental coordination disorder as well as affecting children born prematurely.

The goal is to use the new brain imaging technique to detect these disorders before they manifest themselves in children's behaviour later on.

"At a young age, children may behave the same," notes Spencer, who's also affiliated with the Delta Center and whose department is part of the College of Liberal Arts and Sciences, "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."

Plenty of research has gone into better understanding visual working memory in children and adults. Those prior studies divined neural networks in action using function magnetic resonance imaging (fMRI).

That worked great for adults, but not so much with children,­ especially young ones, whose jerky movements threw the machine's readings off kilter.

So, Spencer and his team turned to functional near-infrared spectroscopy (fNIRS), which 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."

Like fMRI, fNIRS records neural activity by measuring the difference in oxygenated blood concentrations anywhere in the brain.

You've likely seen similar technology when a nurse puts your finger in a clip to check your circulation. In the brain, when a region is activated, neurons fire like mad, gobbling up oxygen provided in the blood.

Those neurons need another shipment of oxygen-rich blood to arrive to keep going. The fNIRS measures the contrast between oxygen-rich and oxygen-deprived blood to gauge which area of the brain is going full tilt at a point in time.

The researchers outfitted the youngsters with colorful, comfortable ski hats in which fiber optic wires had been woven.

The children played a computer game in which they were shown a card with one to three objects of different shapes for two seconds.

After a pause of a second, the children were shown a card with either the same or different shapes. They responded whether they had seen a match.

The tests revealed novel insights. First, neural activity in the right frontal cortex was an important barometer of higher visual working memory capacity in both age groups.

This could help clinicians evaluate children's visual working memory at a younger age than before, and work with those whose capacity falls below the norm, the researchers say.

Secondly, 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 and the first author on the paper.

"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."

Autism: Hyperconnectivity found in children's brains

The brains of children with autism show higher-than-normal connectivity along many neural networks, a new study from the Stanford University School of Medicine has found.

The study's results may contribute to the development of a brain-based test that could be used to diagnose autism at an early stage.

The findings, published June 26 in JAMA Psychiatry, were unexpected because they contradict prior reports of reduced brain connectivity in adults with autism.

Vinod Menon

"We found that in the brains of children with autism there is a surprisingly high level of hyperconnectivity," said Vinod Menon, PhD, senior author of the study.

Menon is a professor of psychiatry and behavioral sciences at Stanford and a member of the Child Health Research Institute at Lucile Packard Children's Hospital.

Based on measurements taken when the brain was at rest—while study participants were awake but had their eyes closed—at least five major brain networks were hyperconnected in kids with autism.

But the finding was not uniform across the brain; some networks were underconnected.

"We found that there are major differences in the way the brain is functionally organized in children with autism—in how different brain areas are talking to each other," Menon said.

"The challenge is to figure out how these differences contribute to the complex profile of clinical symptoms that characterise autism."

The research team collected functional and structural magnetic resonance imaging scans from 20 children with autism and 20 typically developing children.

Assessment of connectivity was based on observing whether different areas of the brain were activated simultaneously: "Spontaneous synchronization of brain signals across long distances is what underlies the hyperconnectivity we detected," Menon said.

Hyperconnected systems in the brains of children with autism included the salience, default mode, fronto-temporal, motor and visual networks.

The salience network, which was the most heavily hyperconnected in autism, integrates information about outside stimuli with information about internal states, allowing the brain to decide which external stimuli to pay attention to.

Menon's team suggests that the hyperconnected salience network may contribute to decreased interest in social interactions among children with autism.

The new study also raises the possibility that brain scans could someday be used to diagnose autism: It found that hyperconnectivity in the salience network distinguished children with autism with 83 percent accuracy.

The team confirmed this finding with a second, independent set of brain scans from 15 children with autism and 15 typically developing children, which were obtained from a public database.

No diagnostic test based on biological markers currently exists for autism; at present, the diagnosis is based solely on observations of a child's behavior, which means that many children are diagnosed later than would be ideal.

Lucina Uddin

"We are optimistic that the brain network metrics we have identified may be used to help in developing strategies for earlier diagnosis, leading to the possibility of earlier interventions," said Lucina Uddin, PhD, an instructor in psychiatry and behavioural sciences and the study's lead author.

The complete implications of brain hyperconnectivity in children with autism are not entirely clear. In the new study, for instance, the degree of hyperconnectivity in the salience network predicted the severity of a child's restricted and repetitive behaviours—such as intense focus on a particular object or interest—frequently seen in autism.

"We think there might be a relative inability for certain types of external stimuli to engage the brain's attentional system," Menon said.

"As a result, a child with autism may be engrossed in a narrow range of behaviours instead of adaptively responding to external stimuli. That's a hypothesis we plan to test."

It's possible that hyperconnectivity could also contribute to epileptic seizures, which are more common in individuals with autism than in the general population.

Future research could also explore whether hyperconnectivity explains unusual skills seen in some individuals with autism, such as outstanding mnemonic, mathematical or spatial abilities.

"Whether hyperconnectivity can lead to exceptional skills, albeit in restricted domains, is an open question," Menon said. "We don't have answers to that yet."

ADHD: Research shows how Ritalin affects Children's brains

Ritalin activates specific areas of the brain in children with attention-deficit/hyperactivity disorder (ADHD), mimicking the brain activity of children without the condition, a new review says.

"This suggests that Ritalin does bring the brain [of a child with ADHD] back to the brain the typically developing kid has," said study author Constance Moore, associate director of the translational center for comparative neuro-imaging at the University of Massachusetts Medical School.

Analyzing data from earlier studies that looked at how children's brains were affected by doing certain tasks that are sometimes challenging for kids with ADHD, the researchers found that Ritalin (methylphenidate) was having a visible impact on three areas of the brain known to be associated with ADHD: the cortex, the cerebellum and the basal ganglia.

Constance Moore

The study could be helpful in diagnosing and treating children with ADHD, Moore said. "It may be helpful to know that in certain children, Ritalin is having a physiological effect in the areas of the brain involved with attention and impulse control," she said.

The research was published recently in the Harvard Review of Psychiatry.

Nine studies analyzed by the researchers used functional MRI to evaluate brain changes after children had taken a single dose of Ritalin.

The children were involved in different types of tasks that tested their ability to focus and inhibit an impulse to act.

For example, to observe the brain's reaction during a test of what is called "inhibitory control," a child was told that every time he saw a zero show up on a screen, he should push the button on the right; every time he saw an X appear, he should push the left button.

The children would then be asked to flip their responses, pushing the left button when they saw a zero.

"That's hard to do," Moore said, "because you've developed the habit [of pushing the other button], so you have to suppress your impulse.

If you do 20 zeros and keep pressing and then you see an X, most kids with ADHD will hit the wrong button."

In three out of five of the inhibitory control studies, Ritalin at least partially normalized brain activation in ADHD children.

To note how the brain reacted to a selective attention test, Moore said, children would first be asked, for example, what word they were seeing.

The word would be "red," and the colour of the type also would be red. Then they would be shown the word "red," but the colour of the type would be green.

In several studies, Ritalin affected activation in the frontal lobes during such inhibitory control tasks. Most of the studies included in the review were performed in the United States or the United Kingdom.

The majority of participants were adolescent boys, and all studies compared their results to healthy children of the same approximate age.

Because none of the studies looked at the correlation between ADHD symptoms and whether the child was taking Ritalin, there is no way to link the changes in brain activation with clinical improvement, Moore said.

"It's possible that kids who are not responsive to Ritalin may have brain changes too," she said. ADHD affects between 3 percent and 7 percent of school-aged children in the United States, according to the American Psychiatric Association.

Boys are more likely to have ADHD than girls. One expert was not surprised by the results.

Andrew Adesman

"The review article shows there is a consensus of well-designed imaging studies showing that [Ritalin] has an impact on the frontal cortex of the brain, where we have long believed these patients have issues," said Dr. Andrew Adesman, chief of developmental and behavioural pediatrics at the Steven & Alexandra Cohen Children's Medical Center of New York, in New Hyde Park.

Adesman wondered if Ritalin may play a role in helping the brain mature. "Their data provides partial support for that," he said.

"But if anything, the medicine seems to help the brain look more normal and doesn't seem to do anything bad to it."

More information: Learn more about ADHD from the U.S. Centers for Disease Control and Prevention.