Transcranial high-frequency random noise stimulation does not modulate Nogo N2 and Go/Nogo reaction times in somatosensory and auditory modalities

Transcranial random noise stimulation (tRNS) of the primary sensory or motor cortex can improve sensorimotor functions by enhancing circuit excitability and processing fidelity. However, tRNS is reported to have little effect on higher brain functions, such as response inhibition when applied to associated supramodal regions. These discrepancies suggest differential effects of tRNS on the excitability of the primary and supramodal cortex, although this has not been directly demonstrated. This study examined the effects of tRNS on supramodal brain regions on somatosensory and auditory Go/Nogo task performance, a measure of inhibitory executive function, while simultaneously recording event-related potentials (ERPs). Sixteen participants received sham or tRNS stimulation of the dorsolateral prefrontal cortex in a single-blind crossover design study. Neither sham nor tRNS altered somatosensory and auditory Nogo N2 amplitudes, Go/Nogo reaction times, or commission error rates. The results suggest that current tRNS protocols are less effective at modulating neural activity in higher-order cortical regions than in the primary sensory and motor cortex. Further studies are required to identify tRNS protocols that effectively modulate the supramodal cortex for cognitive enhancement.