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Low frequency oscillations such as alpha (8-12 Hz) are hypothesized to rhythmically gate sensory processing, reflected by 40-100 Hz gamma band activity, via the mechanism of pulsed inhibition. We applied transcranial alternating current stimulation (TACS) at individual alpha frequency (IAF) and flanking frequencies (IAF-4 Hz, IAF+4 Hz) to the occipital cortex of healthy human volunteers during concurrent magnetoencephalography (MEG), while participants performed a visual detection task inducing strong gamma-band responses. Occipital (but not retinal) TACS phasically suppressed stimulus-induced gamma oscillations in the visual cortex and impaired target detection, with stronger phase-to-amplitude coupling predicting behavioral impairments. Retinal control TACS ruled out retino-thalamo-cortical entrainment resulting from (subthreshold) retinal stimulation. All TACS frequencies tested were effective, suggesting that visual gamma-band responses can be modulated by a range of low frequency oscillations. We propose that TACS-induced membrane potential modulations mimic the rhythmic change in cortical excitability by which spontaneous low frequency oscillations may eventually exert their impact when gating sensory processing via pulsed inhibition.

Original publication

DOI

10.1016/j.neuroimage.2018.09.047

Type

Journal article

Journal

Neuroimage

Publication Date

01/01/2019

Volume

184

Pages

440 - 449

Keywords

Alpha, Gamma, Phase-amplitude coupling (PAC), TACS-MEG, Visual cortex, Visual detection, Female, Gamma Rhythm, Humans, Magnetoencephalography, Male, Transcranial Direct Current Stimulation, Visual Cortex, Visual Perception, Young Adult