with early-stage Alzheimer’s disease. As you probably know, Alzheimer’s is a progressive disease affecting the brain, which generally starts showing effects on people in their 60s and 70s. In the early and middle stages, it is marked by major declines in memory, understanding, and problem-solving. The brain’s frontal lobes are one of the areas that are especially affected during this stage. Parts of the frontal lobes, particularly the dorsolateral prefrontal cortex (dorso for “upper,” lateral “for side”), are important for many kinds of memory, reasoning, and problem-solving. Stimulating these areas regularly for a few weeks produced substantial improvements in memory and problem-solving, and these gains held for up to 4 and a half months.[vi]
Another set of studies looked at the learning of mathematics. In these studies, the researchers wanted to see whether stimulating particular parts of the brain can speed the learning of numerical digits or arithmetic. The problem with both of these is that you can’t teach them to adults—they already know! So, in these studies, the researchers created “new math” and taught it to people in the lab. In the first study, the scientists taught people a new set of symbols representing numerical digits. They used a training task designed to approximate what it is like to learn your numbers for the first time. Each of the participants practiced for six 2-hour sessions. During the training sessions some of them were receiving mild electric stimulation to their right parietal cortex. This area is known to be important for numerical cognition; lesions in it produce a syndrome called dyscalculia, which is a specific impairment of numerical thinking. At the end of the training, the researchers used several tests to see how well participants had learned the numerical value of the symbols. Those who had received stimulation to the right parietal cortex had learned the new digits better than those who received sham stimulation or stimulation to the left hemisphere. In the second study, the scientists taught people a new version of arithmetic and some of the learners received stimulation of their dorsolateral prefrontal cortex, a region in the front of the brain that is important for juggling information during problem-solving. In a final test of the new arithmetic, the students who had received the stimulation performed better. As we learn more about how these stimulation effects work, we may be able to target them and thereby increase the efficacy.[vii]
Why does the brain stimulation meme come up again and again in movies? I think part of it is that we’re all suckers for getting something for nothing: a new skill, a vacation to mars, a cure for what ails us. And techniques such as electrical stimulation and TMS appeal to me because these are the tools my colleagues and I use in our research. The idea that you can just tweak your brain and make it happen is appealing, no doubt. But all movies are brain tweaks—they just stimulate our brains the old-fashioned way, by putting signals in through the eyes and ears.
[Editor’s note: Jeffrey M. Zacks is the brother of Xconomy cofounder Rebecca Zacks. Their mother is very proud.]
[i] This account comes from ‘Heritage Minutes,’ a series on great Canadians produced by the Canadian government.
[ii] Wagner, Valero-Cabre, & Pascual-Leone (2007).
[iii] Gerschlager, Siebner, & Rothwell (2001).
[iv] The stimulation of the temporal lobes to treat depression long predates TMS. In electroconvulsive therapy (ECT), a strong electric current is passed through the brain to induce a seizure affecting the medial temporal lobes. This is an effective treatment, but the seizure carries some risks and the experience is quite unpleasant. TMS allows physicians to disrupt function more focally, limiting risks and side effects.
[v] Reis, Robertson, Krakauer, Rothwell, Marshall, Gerloff, et al. (2008).
[vi] Boggio, Valasek, Campanhã, Giglio, Baptista, Lapenta, et al. (2011).
[vii] The digit learning study is reported in Cohen Kadosh, Soskic, Iuculano, Kanai, and Walsh (2010). The arithmetic study is reported in Snowball, Tachtsidis, Popescu, Thompson, Delazer, Zamarian, et al. (2013). A recent issue of the journal NeuroImage was devoted to the topic of enhancing cognition with magnetic and electrical stimulation. This opening article by Clark and Parasuraman (2014) gives a nice overview of the topic.
