Increasing Human Brain Excitability by Transcranial High-Frequency Random Noise Stimulation

TLDR

For >20 years, noninvasive transcranial stimulation techniques such as rTMS and tDCS have been used to induce neuroplastic‑like effects in the human cortex, leading to activity‑dependent modification of synaptic transmission. The study introduces transcranial random noise stimulation (tRNS) as a novel electrical stimulation method applied over the motor cortex. tRNS delivers a random electrical oscillation spectrum over the motor cortex. tRNS consistently increases cortical excitability for up to 60 min, as shown in 80 subjects through physiological and behavioral measures, with high‑frequency components (100–640 Hz) likely driving the effect via repeated opening of Na⁺ channels, and demonstrating therapeutic potential comparable to rTMS/tDCS for depression.

Abstract

For >20 years, noninvasive transcranial stimulation techniques like repetitive transcranial magnetic stimulation (rTMS) and direct current stimulation (tDCS) have been used to induce neuroplastic-like effects in the human cortex, leading to the activity-dependent modification of synaptic transmission. Here, we introduce a novel method of electrical stimulation: transcranial random noise stimulation (tRNS), whereby a random electrical oscillation spectrum is applied over the motor cortex. tRNS induces consistent excitability increases lasting 60 min after stimulation. These effects have been observed in 80 subjects through both physiological measures and behavioral tasks. Higher frequencies (100–640 Hz) appear to be responsible for generating this excitability increase, an effect that may be attributed to the repeated opening of Na + channels. In terms of efficacy tRNS appears to possess at least the same therapeutic potential as rTMS/tDCS in diseases such as depression, while furthermore avoiding the constraint of current flow direction sensitivity characteristic of tDCS.