Trouble With Math? Maybe You Should Get Your Brain Zapped


by Emily Underwood

If you are one of the 20% of healthy adults who struggle with basic arithmetic, simple tasks like splitting the dinner bill can be excruciating. Now, a new study suggests that a gentle, painless electrical current applied to the brain can boost math performance for up to 6 months. Researchers don’t fully understand how it works, however, and there could be side effects.

The idea of using electrical current to alter brain activity is nothing new—electroshock therapy, which induces seizures for therapeutic effect, is probably the best known and most dramatic example. In recent years, however, a slew of studies has shown that much milder electrical stimulation applied to targeted regions of the brain can dramatically accelerate learning in a wide range of tasks, from marksmanship to speech rehabilitation after stroke.

In 2010, cognitive neuroscientist Roi Cohen Kadosh of the University of Oxford in the United Kingdom showed that, when combined with training, electrical brain stimulation can make people better at very basic numerical tasks, such as judging which of two quantities is larger. However, it wasn’t clear how those basic numerical skills would translate to real-world math ability.

To answer that question, Cohen Kadosh recruited 25 volunteers to practice math while receiving either real or “sham” brain stimulation. Two sponge-covered electrodes, fixed to either side of the forehead with a stretchy athletic band, targeted an area of the prefrontal cortex considered key to arithmetic processing, says Jacqueline Thompson, a Ph.D. student in Cohen Kadosh’s lab and a co-author on the study. The electrical current slowly ramped up to about 1 milliamp—a tiny fraction of the voltage of an AA battery—then randomly fluctuated between high and low values. For the sham group, the researchers simulated the initial sensation of the increase by releasing a small amount of current, then turned it off.

For roughly 20 minutes per day over 5 days, the participants memorized arbitrary mathematical “facts,” such as 4#10 = 23, then performed a more sophisticated task requiring multiple steps of arithmetic, also based on memorized symbols. A squiggle, for example, might mean “add 2,” or “subtract 1.” This is the first time that brain stimulation has been applied to improving such complex math skills, says neuroethicist Peter Reiner of the University of British Columbia, Vancouver, in Canada, who wasn’t involved in the research.

The researchers also used a brain imaging technique called near-infrared spectroscopy to measure how efficiently the participants’ brains were working as they performed the tasks.

Although the two groups performed at the same level on the first day, over the next 4 days people receiving brain stimulation along with training learned to do the tasks two to five times faster than people receiving a sham treatment, the authors reported in Current Biology. Six months later, the researchers called the participants back and found that people who had received brain stimulation were still roughly 30% faster at the same types of mathematical challenges. The targeted brain region also showed more efficient activity, Thompson says.

The fact that only participants who received electrical stimulation and practiced math showed lasting physiological changes in their brains suggests that experience is required to seal in the effects of stimulation, says Michael Weisend, a neuroscientist at the Mind Research Network in Albuquerque, New Mexico, who wasn’t involved with the study. That’s valuable information for people who hope to get benefits from stimulation alone, he says. “It’s not going to be a magic bullet.”

Although it’s not clear how the technique works, Thompson says, one hypothesis is that the current helps synchronize neuron firing, enabling the brain to work more efficiently. Scientists also don’t know if negative or unintended effects might result. Although no side effects of brain stimulation have yet been reported, “it’s impossible to say with any certainty” that there aren’t any, Thompson says.

“Math is only one of dozens of skills in which this could be used,” Reiner says, adding that it’s “not unreasonable” to imagine that this and similar stimulation techniques could replace the use of pills for cognitive enhancement.

In the future, the researchers hope to include groups that often struggle with math, such as people with neurodegenerative disorders and a condition called developmental dyscalculia. As long as further testing shows that the technique is safe and effective, children in schools could also receive brain stimulation along with their lessons, Thompson says. But there’s “a long way to go,” before the method is ready for schools, she says. In the meantime, she adds, “We strongly caution you not to try this at home, no matter how tempted you may be to slap a battery on your kid’s head.”

Have scientists rendered the final word on penis size?


No man is an island, and it turns out neither is his penis. New research suggests that size does matter (sorry, guys), but the penis is only one (sometimes) small contributor to manly allure. A man’s overall attractiveness to a woman, researchers have found, depends in part on the trio of height, body shape, and penis size.

Although the assault of penis pill spam in your inbox might make you think that “bigger is better,” scientific research has returned mixed results. Some findings say that women prefer longer penises, others say they like wider ones, and still others report that size doesn’t matter at all.

Most of these studies had either asked women directly about their preferences or had them rate the attractiveness of different male figures that varied only in penis length. The penis doesn’t exist in a vacuum, though, and biologists led by Brian Mautz, who was then at the Australian National University in Acton, wondered how penis size interacts with other body traits that are usually considered attractive or manly.

Using data from a large study of Italian men, the researchers created 343 computer-generated male figures that varied in penis size, as well as in height and shoulder-to-hip ratio—traits that other research has linked to attractiveness and reproductive success. Mautz and colleagues turned the figures into short video clips and projected them, life-sized, onto a wall for viewing by 105 women. Each woman watched a random set of 53 figures and rated their attractiveness as potential sexual partners on a scale of 1 to 7.

“The first thing we found was that penis size influences male attractiveness,” Mautz says. “There’s a couple of caveats to that, and the first is that the relationship isn’t a straight line.” Rather than the attractiveness rating consistently improving with each jump in penis size, the team found what Mautz calls “an odd kink in the middle.” Attractiveness increased quickly until flaccid penis length reached 7.6 centimeters (about 3 inches) and then began to slow down, the team reports online today in the Proceedings of the National Academy of Sciences.

The reason, Mautz says, is that penis size isn’t the only thing that matters. It interacts with other traits, and its effect depends on whether those other traits are already attractive to begin with. If one of the model men was tall and had a masculine, V-shaped torso with broad shoulders and narrower hips, for example, he was considered more attractive than his shorter, stockier counterparts, regardless of penis size.

An increase in penis size was also a bigger benefit to attractiveness, and a smaller penis was less of a detriment, to the taller, fitter figures than it was to shorter or potato-shaped ones. For example, a model that was 185 cm tall (about 6 ft) with a 7-cm-long (about 3-in-long) penis got an average score for attractiveness. To get that same score, a model that was 170 cm (about 5’6″) needed a penis of about 11 cm (about 4.5 in) in length. Boost the taller guy’s penis by just about centimeter, and the shorter guy needs double that to keep up and get the same attractiveness score. After that, the shorter male pretty much can’t continue to compete. To really reap the benefits of a big penis, a guy needs to be attractive in the first place, Mautz says. If he isn’t, even the biggest penis in the world won’t do him that much good.

So have women been responsible for the male penis getting larger—at least over the course of evolution? That’s a distinct possibility, the researchers say. Women may have selected for larger penises because they’re linked to higher rates of female orgasm and sexual satisfaction, which may explain why the human penis is proportionally larger than those of our evolutionary cousins.

That size matters, and that it matters in the context of other traits, makes sense, because proportionate features are attractive, says Adam Jones, a biologist who studies sexual selection and mate choice at Texas A&M University in College Station and who was not involved in the work. But he cautions that projections on a wall are no substitute for real life. Just because a woman prefers a man with a large penis doesn’t mean that she’s going to find one. Outside the lab, there’s greater variation and more traits to consider, so penis size might not be as important. That’s good, Jones says, because hurdles like competition with other women and her own perceived attractiveness could place her with a man who comes up a little short.

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

Ancient urine provides clues to Africa’s past


When it comes to peering into Africa’s climate past, the ancient homes of hyraxes are number one. Paleoclimatologists typically dig up muddy core samples and analyze their pollen content for clues to long-ago weather, but parts of southern and central Africa are too dry to preserve such evidence. Enter the rock hyrax (Procavia capensis) (inset), a furry mammal that looks like a large groundhog but is actually a distant cousin of the elephant. Brian Chase, a geographical scientist at the University of Montpellier in France, turned to urine accretions left by the animals thousands of years ago; hyrax colonies use the same rock shelters for generation after generation, depositing pollen, calcium remnants, charcoal particles, stable isotopes, and other detritus in their urine (black splotches on rock in main image). Most climate models predict arid conditions in southern Africa 12,000 years ago, but the pollen content of hyrax urine from that period indicates that they ate grasses, which flourish in wetter conditions Chase, who reported his findings here today at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW), believes his method can be used to give researchers a wealth of data to improve their models of Africa’s paleohistory. “You can turn a 2-meter pile of pee into a very nice section which you can bring back to the lab,” he told the audience. “These are very high-resolution records.”

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Intereting community.