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Left, right brains collaborate for math ability

Mathematical ability may be strengthened by interaction between the left and right sides of the brain, a study found.

Researchers at Duke University, the University of Michigan and the University of Texas at Dallas showed that arithmetic performance is correlated to heightened levels of communication between the left and right hemispheres of the brain. The findings may lead to treatment methods for cognitive problems with mathematics and for age-induced mental decline.

Previous research showed that the right region of the brain’s parietal cortex handles basic quantity processing and the left parietal region contributes to numerical operations. The connectivity between these two halves contributes to numerical competence and arithmetic processing, according to the study, published online this summer in the journal Cerebal Cortex.

“Crosstalk between [both] brain regions was most effectively [occurring] when subjects were solving an arithmetic problem that involved adding or subtracting numbers,” Joonkoo Park, postdoctoral fellow and lead author of the study, wrote in an email Sept. 6. “We thus speculate that mental manipulation of numbers require such crosstalk.”

To examine neural activity and interconnectivity, the researchers used functional magnetic resonance imaging while subjects performed simple numerical and arithmetic tasks like addition and subtraction, said Dr. Thad Polk, professor of psychology at the University of Michigan.

The fMRI estimated neural activity throughout the brain while people perform different tasks.

“Using these readings, we then contrasted neural activity and connectivity in one condition versus another and drew connections between these differences based on task specificity,” Polk said.

Basic quantity processing tasks such as number matching activated the right parietal cortex, while acquired arithmetic processing tasks such as addition and subtraction activated the left parietal cortex, Park noted.

What was unexpected, however, was the significant increase in communication between the left and right hemispheres during arithmetic tasks than in control conditions, he said.

“What we found was phenomenal because mathematical operations do not just depend on how much neural activity is occurring in the brain but also on how interconnected the activity is,” said Denise Park, co-director of the Center for Vital Longevity at UT Dallas. “With this discovery, I think people who are studying the neuroscience of mathematical processing will shift their focus from studying individual neural sites to studying a network comprised of individual processes.”

Although there is a long way to go before these findings can be applied to interventions, they might help in treating developmental learning disorders such as dyscalculia, the numerical equivalent of dyslexia, said Joonkoo Park.

“In the future, we may expect to develop better screening methods for examining dyscalculia based on functional connectivity and more efficient training paradigms focused on improving numerical competence,” he said.

Denise Park added that such training paradigms could also help elderly adults rebuild neural connections required for mathematical processing after onset of age-related cognitive decline.

“Examining how experience and aging play a role in changing neural connectivity is something that I am particularly interested in,” she said. “I especially want to study how calculator usage has impacted neural connectivity in the brain by comparing younger and older populations’ mental calculation processing abilities.”

Joonkoo Park hopes to extrapolate these findings to other learning disabilities by utilizing more complex mathematical problems. He also hopes to examine effects of behavioral training on the degree of interconnectivity.

“Functional connectivity has been one important approach to studying dyslexia, but results like our current study will further emphasize the role of neural interconnectivity in developmental learning disorders,” Joonkoo Park said.

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