New brain-imaging research reveals how the brain reorganizes itself as children learn basic math facts.
“As children learn basic arithmetic, they go from solving problems by counting on their fingers to pulling facts from memory,” researchers at the Stanford University School of Medicine said. “The shift comes more easily for some kids than for others, but no one knows why,” the researchers said.
Their new study shows that a precisely orchestrated group of brain changes, many involving the memory center known as the hippocampus, are critical to the transformation.
“We wanted to understand how children acquire new knowledge, and determine why some children learn to retrieve facts from memory better than others,” said Vinod Menon, Ph.D., professor of psychiatry and behavioral sciences and the senior author of the study.
“This work provides insight into the dynamic changes that occur over the course of cognitive development in each child.”
The study also adds to previous research into the differences between how children’s and adults’ brains solve math problems, he noted. Children use certain brain regions, including the hippocampus and the prefrontal cortex, very differently from adults when the two groups are solving the same types of math problems, the study showed.
“It was surprising to us that the hippocampal and prefrontal contributions to memory-based problem-solving during childhood don’t look anything like what we would have expected for the adult brain,” said postdoctoral scholar Shaozheng Qin, Ph.D., the paper’s lead author.
For the study, 28 children solved math problems while receiving two functional magnetic resonance imaging brain scans. The scans were done about 1.2 years apart. The researchers also scanned 20 adolescents and 20 adults at a single point in time.
At the start of the study, the children were between the ages of seven and nine. The adolescents were 14 to 17 and the adults were 19 to 22. All participants had normal IQs.
Because the study examined normal math learning, potential participants with math-related learning disabilities and attention deficit hyperactivity disorder were excluded, the researchers noted.
During the study, as the children aged from an average of 8.2 to 9.4 years, they became faster and more accurate at solving math problems, and relied more on retrieving math facts from memory and less on counting, according to the researchers.
As these shifts in strategy took place, the researchers saw several changes in the children’s brains. The hippocampus, a region with many roles in shaping new memories, was activated more in children’s brains after one year, they discovered. Regions involved in counting, including parts of the prefrontal and parietal cortex, were activated less, they found.
The researchers also saw changes in the degree to which the hippocampus was connected to other parts of children’s brains, with several parts of the prefrontal, anterior temporal cortex, and parietal cortex more strongly connected to the hippocampus after one year.
“The stronger these connections, the greater the child’s ability to retrieve math facts from memory, a finding that suggests a starting point for future studies of math-learning disabilities,” the researchers said.
Although children were using their hippocampus more after a year, adolescents and adults made minimal use of their hippocampus while solving math problems, according to the researchers. Instead, they pulled math facts from well-developed information stores in the neocortex.
“What this means is that the hippocampus is providing a scaffold for learning and consolidating facts into long-term memory in children,” Menon said.
The hippocampus helps support other parts of the brain as adult-like neural connections for solving math problems are being constructed, he explained.
“In adults this scaffold is not needed because memory for math facts has most likely been consolidated into the neocortex,” he said.
“Interestingly,” he said, “the research also showed that while the adult hippocampus is not as strongly engaged as in children, it seems to keep a backup copy of the math information that adults usually draw from the neocortex.”
The researchers also compared the level of variation in patterns of brain activity as children, adolescents, and adults correctly solved math problems. The brain’s activity patterns were more stable in adolescents and adults than in children, suggesting that as the brain gets better at solving math problems, its activity becomes more consistent, the researchers reported.
The next step is to compare the new findings about normal math learning to what happens in children with math-learning disabilities, according to Menon.
“In children with math-learning disabilities, we know that the ability to retrieve facts fluently is a basic problem, and remains a bottleneck for them in high school and college,” he said.
“Is it that the hippocampus can’t provide a reliable scaffold to build good representations of math facts in other parts of the brain during the early stages of learning, and so the child continues to use inefficient strategies to solve math problems? We want to test this.”
The study was published in Nature Neuroscience.