If Tyler is right, it could explain why tDCS results have been so hard to replicate. Researchers position tDCS electrodes based on the assumption that they affect the areas of the brain directly below. But sometimes they may be accidentally stimulating the cranial nerves instead, leading to inconsistent results. Based on his new hypothesis, Tyler changed where he placed the electrodes, targeting these nerves specifically.

Early experiments showed enough of an effect to suggest the hypothesis was right, Tyler says. But the effects weren’t huge. The next step was to amplify the effect by increasing current levels without causing pain or skin damage. Researchers at Thync, which was founded in 2011, did this in part by using pulses of electricity, rather than steady current, and operating at frequencies that don’t stimulate pain receptors.

I experienced the difference that these measures make when I tried out a conventional tDCS device side-by-side with Thync’s technology. At three or four milliamps of electrical current, conventional tDCS was quite painful. That’s why most experiments are done at around one milliamp. In contrast, I couldn’t even feel the pulses from Thync’s device at 10 milliamps.

via Coming Soon—Electronic Mood Control | MIT Technology Review.