### Math ability requires hemisphere crosstalk in the brain

##### August 31, 2012

The strength of communication between the left and right hemispheres of the brain predicts performance on basic arithmetic problems, a new study by researchers at UT Dallas’ Center for Vital Longevity, Duke University, and the University of Michigan has found.

The findings shed light on the neural basis of human math abilities and suggest a possible route to aiding those who suffer from *dyscalculia* — an inability to understand and manipulate numbers.

**Two hemispheres work together to improve math performance**

It has been known for some time that the parietal cortex, the top/middle region of the brain, plays a central role in numerical cognition — our ability to process numerical information.

Previous brain imaging studies have shown that the right parietal region is primarily involved in basic quantity processing (like gauging relative amounts of fruit in baskets), while the left parietal region is involved in more precise numerical operations like addition and subtraction.

What has not been known is whether the two hemispheres can work together to improve math performance. The new study demonstrates that they can.

In the study (supported by a grant to Dr. Denise C. Park from the National Institute on Aging) conducted in Dallas and led by Dr. Joonkoo Park, now a postdoctoral fellow at Duke University, researchers used functional magnetic resonance imaging (fMRI) to measure the brain activity of 27 healthy young adults while they performed simple numerical and arithmetic tasks.

In one task, participants were asked to judge whether two groups of shapes contained the same or different numbers of items. In two other tasks, participants were asked to solve simple addition and subtraction problems.

Consistent with previous studies, the researchers found that the basic number-matching task activated the right parietal cortex, while the addition and subtraction tasks produced additional activity in the left parietal cortex.

But they also found something new: During the arithmetic tasks, communication between the left and right hemispheres increased significantly compared with the number-matching task. Moreover, people who exhibited the strongest connection between hemispheres were the fastest at solving the subtraction problems.

“Our results suggest that subtraction performance is optimal when there is high coherence in the neural activity in these two brain regions. Two brain areas working together rather than either region alone appears to be key” said co-author Dr. Denise C. Park, co-director of the UT Dallas Center for Vital Longevity and Distinguished University Chair in the School of Behavioral and Brain Sciences. Park (no relation to the lead author) helped direct the study along with Dr. Thad Polk, professor of psychology at the University of Michigan.

Lead author Dr. Joonkoo Park points out that the findings suggest that disrupted or inefficient neural communication between the hemispheres may contribute to the impaired math abilities seen in dyscalculia, the numerical equivalent of dyslexia. “If such a causal link exists,” he said, “one very interesting avenue of research would be to develop training tasks to enhance parietal connectivity and to test whether they improve numerical competence.”

Such a training program might help develop math ability in children and could also help older adults whose arithmetic skills begin to falter as a normal part of age-related cognitive decline.

What kinds of devices or exercises would be most effective for this hemispheric brain synchronization training? Would “mind machines” work? (There has been very little research on this so far.)

## comments 16

September 2, 2012by trakk

So if right and left parietal are interconnected its math, then right and left temporal..science or other non numerical skills?? and right and left frontal…leadership?? I hope somebody test this out too.

September 2, 2012by snake0

There is a version of the ‘God Helmet’ which uses electromagnetic pulses to shut off connectivity in the brain and imposes a temporary autistic state in the user, which is then reported to have enhanced capabilities in number matching and mathematics, which would seem to contradict this article because it is effectively limiting the communication between right and left hemisphere (however this may be forcing communication between hemispheres to occur through some other ‘higher bandwidth’ route).

September 2, 2012by Editor

I want to thank you for this comment, which led me to some interesting explorations. You are describing transcranial magnetic stimulation. TMS actually only blocks connectivity to the left (conceptual) hemisphere, which temporarily induces disinhibition of the right (perceptual) hemisphere, according to TMS research Allan Snyder*. The result is to heighten perception, leading to savant-like abilities, including amazing abilities to remember huge numbers.

Note that the study at UT Dallas/Duke/Michigan found that the number-matching task activated the right parietal cortex (as in TMS), while the addition and subtraction tasks produced additional activity in the left parietal cortex — more so with subtraction, which requires greater conceptual skill.

That seems consistent with Snyder’s findings. I’m going to ask Snyder to comment on this.

Maybe there’s a way to use TMS to improve the right-brain aspects of math? It seems Einstein called on direct perceptual understanding.

* See Conversations on Creativity with Allan Snyder,

http://www.psychologytoday.com/blog/beautiful-minds/201001/conversations-creativity-allan-snyder.

September 1, 2012by Brian Jauw

I wonder if this is explanation for the [debatable] correlation between instrumental musicians and better scores on mathematics assessments. It has been noted several times that people who train on musical instruments from a young age develop thicker corpus callosums.

August 31, 2012by Karl Haglin

For me at least, subtraction requires more steps. Let’s say I wanna calculate 53-38.

1) First I store 38 in my memory.

2) Then I reduce 53 by 8, so I get 45

3) Then I store 45

4) Then I go back to 38, strip away 8 so I get 30

5) Then I go back to 45 and reduce with 30 = 15

I can feel how things really turn in my head when I’m at step 2-4. When I add on the other hand add I don’t feel I need to store as much and I can go for directly for it without thinking. Let’s say I wanna calculate 53+38:

1) First I store 38 in my memory

2) Then I take 8 and add it to 53 so I get 61.

3) Then I have 30 left and I added to 61 to get 91.

August 31, 2012by Foye Lowe

Interesting. I might use some of the rote methods taught in school (8 from 13, borrowing “one” from the 5, etc.); or, I more often would note that the difference between 38 and 48 is 10, and the difference between 48 and 50 is 2, and between 50 and 53 is 3; ergo, 10 + 2 + 3 = a difference of 15 between 53 and 38. There’s more than one way around the mulberry bush . . .

August 31, 2012by Guillermo

Interesting to see the many ways there are for doing the same thing (reminds me of a Feynman video..). The way I actually do it most of the time is to start adding numbers to 38, i.e.:

38+10=48

48+5=53

so 53-38=15.

I guess my brain likes the concept of adding more, so it translates the substracting problem into an adding one :)

September 2, 2012by trakk

I imagine a chart with numbers 1 to 100 with each column having ten numbers obviously, and then substract.

August 31, 2012by Dr.Pratt

Hold three dice in the left hand and roll them. Feel the tops of the die while blindfolded and write down the quantity with the right hand. Switch hands and do the same task. Add complexity.

August 31, 2012by Dr.Pratt

Since the hemipheres are also connected to handedness, there is a key there on how to design hemispheric connectedness for math tasks. Recognition would be simple by having the subject detect quataties in each hand while blindfolded.

August 31, 2012by Khannea Suntzu

No, I aquired discalculia in my early puberty and it got a lot worse over the years. It is a distinctive disorder. You can’t just blame people who have it, as much as you can’t blame cripples for “not having the proper discipline to walk”. It just isn’t there.

August 31, 2012by SpottedMarley

maybe just practice mathematics? .. is that too obvious?

:)

August 31, 2012by Foye Lowe

Groovy. (Or, more accurately, grooving . . . )

August 31, 2012by bill yarberry

I agree that just doing math works, given the mind’s plasticity. I wonder though if cross disciplinary studies in general help. Maybe just crossing the hemisphere boundaries is the trick? But then again, when Gauss as a three year old corrected his father’s accounting figures … I don’t think any kind of exercise gets you to that exalted state of mathematical power

September 1, 2012by Pete Fowler

There’s much more to it than that. I’ve been good at mental arithmetic since before my first primary school maths lesson. I’ve also been a very slow learner of more advanced maths, even though I’ve sweated blood at it. I had to, in order to continue studying physics, which is my best subject. I’m 64 now.

September 1, 2012by longnow

Gee golly Jimminy Crickets, are you conservatively

“brilliant at breakfast” also?