## Sunday, November 7, 2010

I have fond memories of high school math classes. Numbers came easy for me, and I derived a lot of satisfaction from solving problems (and even more so when I solved them fast!). I was lucky to have excellent teachers, especially in grade 11 and in CEGEP, who turned math into something of a game, a code I needed to crack. However, I’m well aware that math class was not a party for everyone. About 15 to 20% of the population struggle with some form of difficulty in learning or understanding mathematics. Obviously, this can be an obstacle to success in school, and in employment. To address this issue, a team of researchers from the UK set out to test whether brain stimulation could improve someone’s math abilities.

The researchers used a technique called transcranial direct current stimulation (TDCS, similar to the method used in this post on morality). TDCS consists of applying a weak current to a brain region (in this case, the parietal lobe, a region important for learning and understanding of math) over a given time period (in this case, 20 minutes). The technique is non-invasive, meaning they don’t open up your scalp to get at your brain: electrodes are simply place on your head (volunteers are much easier to recruit when the electrodes are on the outside, not the inside). Depending on the type of current that the researchers apply, TDCS can increase or reduce the excitation of the brain cells in the targeted region.

To test the impact of this kind of brain stimulation on math capabilities, the researchers delivered the stimulation while the participants (15 healthy adults) were learning the relative values between nine arbitrary symbols (for example, square is bigger than triangle). The learning session lasted 90 to 120 minutes. The participants received either the brain stimulation during the first 20 minutes of the session (the experimental group), or only during the first 30 seconds of the session (the control group, as 30 seconds of the stimulation is not long enough to see any effects, but still gives you the “tingles” associated with the protocol). After this learning phase, the researchers assessed the participants’ newly created sense of numerical value for the symbols with two different math tasks using the symbols. This whole process was then repeated over six days.

The results show that brain stimulation leads to better and more consistent performance on both math tasks. Mathematical ineptitude is cured! To make the matters even more interesting, the researchers called the participants back six months later and re-tested them (no brain stimulation this time). And six months later, the brain stimulation group still performed better at the math tasks involving the fake digits.

While this may sound great, don’t start tazing your brain just yet. It’s worthwhile to note that on the last day of the initial six-day study, the researchers had the participants perform the same two math tasks, but with normal numbers. In this case, there were no difference between the experimental group and the control group. This means that the brain stimulation paradigm only worked for the specific task that was learned during the stimulation, and didn’t extend to math in general. Nonetheless, the researchers suggest that brain stimulation may be a tool for intervention for those who have “developmental and acquired disorders in numerical cognition” (read: for people who are bad at math).

Must we all be good at math? There’s a French saying that goes: "ça prend toute sorte de monde pour faire un monde" (roughly translates into: "it takes all sorts of people to make a world"). What’s your take on this? Do you think this is a great advance? Do you have any concerns? Let’s hear it!

Reference: Modulating neuronal activity produces specific and long-lasting changes in numerical competence. (2010) Cohen Kadosh R et al. Current Biology 20:1-5.

#### 3 Responses to “Math made easy”

JLoh said...

Very interesting read! I wonder what would happen if they did the same experiment with the same amount of brain stimulation but with the participants reading Shakespeare. My feeling is that the results would be similar because any form of brain stimulation would make one focus more on the task/subject at hand.
I believe that it's important to have a nice, well-rounded understanding of all things...but we do definitely need specialists in every field.

Anonymous said...

I enjoy reading your analysis, SC. But I would virtually explode if a media outlet got a-hold of this study and inflated it for public view. Since you did not hyperbole the results, I enjoy our exchange here and might even re-tweet it.

To even consider this little study has value one has to accept that the groups were evenly homogeneous.

Since you read the study - but I cannot help but ask - you had no questions about the physiological effects in the brain of "weak current" on the surface of the head? Honestly, I can't imagine/believe a single neural cell molecule was changed during stimulation.

Physical therapists use electricity as a treatment modality for muscle activation and pain relief (read on the 'gate theory'). Depth of the current through skin is variable and I'm not sure about current through bone.

Perhaps the method should not be called "brain stimulation" but scalp stimulation - and if it is effective - a different hypothesis for how it works needs to be formulated. Thanks so much for an interesting read. Barbara

@ JLoh: You ask a good question. It's well established that the parietal lobe is important for math, but I wonder if any learning task would work.

@ Barbara: You're absolutely right: things can quickly get out of hand when studies like this one are misinterpreted or described out of context.

It's always difficult to get perfectly homogeneous groups, but in this case, they should start with a larger sample. I think it was mostly a proof of concept type of article.

In terms of the physiological effects of the stimulation, they seem legit based on previous studies. Yes, the scalp is quite the barrier, but neuronal transmission is tiny in magnitude, and so a change of a few millivolts in the membrane potential could impact firing rates. That said, the precise location and magnitude of this effect is hard to evaluate, and so I absolutely agree that this type of experiment is a little bit vague and the cause-and-effect could be assessed more convincingly.

Thanks for the comment!