Very well researched and well-balanced article from Mark Harris at The Economist.
Hardly surprising, then, that DIY brain hackers want in on the action. Christopher Zobrist, a 36-year-old entrepreneur based in Vietnam, is one of them. With little vision he has been registered as blind since birth due to an hereditary condition of his optic nerve that has no established medical treatment. Mr Zobrist read a study of a different kind of transcranial stimulation (using alternating current) that had helped some glaucoma patients in Germany recover part of their vision. Despite neither the condition nor the treatment matching his own situation, Mr Zobrist decided to try tDCS in combination with a visual training app on his tablet computer. He quickly noticed improvements in his distance vision and perception of contrast. “After six months, I can see oncoming traffic two to three times farther away than before, which is very helpful when crossing busy streets,” he says.
Equally troublesome is a meta-analysis of the cognitive and behavioural effects on healthy adults that Mr Horvath subsequently carried out. As before, he included only the most reliable studies: those with a sham control group and replicated by other researchers. It left 200 studies claiming to have discovered beneficial effects on over 100 activities such as problem solving, learning, mental arithmetic, working memory and motor tasks. After his meta-analysis, however, tDCS was found to have had no significant effect on any of them.
If tDCS alters neither the physiology of the brain nor how it performs, thinks Mr Horvath, then evidence suggests it is not doing anything at all. Marom Bikson, a professor of biomedical engineering at City University of New York, disagrees. “I can literally make you fall on your butt using the ‘wrong’ type of tDCS,” he says. Dr Bikson thinks the biggest challenge for tDCS is optimising techniques, such as the dose.
Felipe Fregni, an associate professor at Harvard Medical School who was involved with the research, has a theory on why that happened. “The students ingested fewer calories because they could make more rational decisions,” he says.
He says tDCS may have dialed up the activity in the students’ prefrontal cortices—where the stimulation was applied and where they make rational, considered decisions, which in turn dialed down the students’ initial knee-jerk reaction to eat food when they saw it. This makes good sense: The dorsolateral prefrontal cortex is known to be an area of the brain that enables us to inhibit temptation.
“It’s the part of the brain most developed in humans compared to monkeys, and it relates to some of the more advanced abilities we have,” says Roi Cohen Kadosh, a neuropsychologist at the University of Oxford who is another of the leading lights in tDCS research. “It’s involved in learning and working memory, and it’s highly connected to other brain regions, such as ones involved with addictions and rewards, and food is rewarding.”
The Soterix website and all that shiny new technology!
They make reference to ‘HD-tDCS‘ and diagram multi-electrode application for fine-tuning current distribution. Download their device manual (pdf).
Prof. Bikson’s lab has a YouTube page. They seem to have constructed a computer model for determining where current flows according to how electrodes are placed.
Prof. Bikson’s group uses a range of research and engineering design tools including cellular and animal studies, computer simulations, imaging, and clinical evaluation. Prof. Bikson’s research has recieved support from funding agencies including NIH (NINDS,NCI,NIGMS), The Andy Grove Foundation, The Wallace H. Coulter Foundation, and the Howard Hughes Medical Institute. . Prof. Bikson is actively involved in biomedical education including outreach to underserved groups.