Noninvasive Neuromodulation Goes Deep

Abstract

Modulating deep regions of the brain with noninvasive technology has challenged researchers for decades. In a new study, Grossman et al. leverage the emergence of a slowly oscillating "beat" from intersecting high-frequency electric fields to stimulate deep brain regions, opening a frontier in the biophysics and technology of brain stimulation.

Figure 1. Temporal Interference for Noninvasive Electrical Stimulation of Deep Brain Regions

Two pairs of electrodes on the surface of the head concurrently deliver electric currents oscillating at high but slightly different frequencies (e.g., 2 kHz, blue; 2.01 kHz, orange). In the brain regions near each pair, high-frequency electric fields of corresponding frequency and fixed amplitude are generated. Where the two frequencies overlap, the superposition of the two sinusoids produces a slowly “beating” envelope at a frequency equal to the difference of the two sinusoids (e.g., 10 Hz, blue/orange stripes). While the intensity of the individual high-frequency electric fields is maximal at superficial regions, the intensity of the slow beat frequency peaks in the region marked by equal contribution of both signals, which coincides in this case with the middle of the brain.