The language of the brain is electricity. Electrical signals are critical for cell-to-cell communication, but neurons in the brain don't respond to every signal they feel—they prefer lower frequencies. Stimulating neurons deep in the brain with these signals has been shown to improve symptoms of conditions such as Parkinson's disease and dystonia, but the only way to get them there (without zapping the entire brain) involves brain surgery: the implantation of electrodes. Now, a team led by researchers from the Massachusetts Institute of Technology has forced a mouse's whiskers to wiggle by stimulating deep regions of the brain—from outside the skull.
Unexpectedly, the researchers started with high-frequency electrical fields. Rather than just one, they used two—2,000 Hz and 2,010 Hz. The fields interfered with one another to produce a low 10 Hz signal deep in the brain that was able to excite neurons in a targeted area. In the lab, the researchers were able to move a mouse's whiskers, paw, and ears—proof that they were stimulating their targets.
This technique, known as temporal interference, won't replace invasive deep brain stimulation completely. Some conditions will still require sustained treatment that can only come from implanted electrodes. But for other conditions, such as depression and epilepsy, short sessions of stimulation can provide lasting benefits. Scientists still have to translate the technique to the thicker skulls of humans, and test for safety and precision, but early results are promising.