Low-frequency alternating current stimulation rhythmically suppresses gamma-band oscillations and impairs perceptual performance

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2019-01, Vol.184, p.440-449
• Main Authors: Herring, Jim D., Esterer, Sophie, Marshall, Tom R., Jensen, Ole, Bergmann, Til O.
• Format: Article
• Language: English
• Subjects: Alpha; Behavior; Brain research; Electrodes; Entrainment; Excitability; Female; Gamma; Gamma Rhythm - physiology; Gating; Humans; Information processing; Magnetoencephalography; Magnetoencephalography - methods; Male; Membrane potential; Occipital lobe; Oscillations; Phase-amplitude coupling (PAC); Power; Retina; Rhythms; Sensory integration; Somatosensory cortex; Studies; TACS-MEG; Transcranial Direct Current Stimulation - methods; Visual cortex; Visual Cortex - physiology; Visual detection; Visual Perception - physiology; Young Adult
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2018.09.047

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. •Occipital TACS at individual alpha frequency ±4 Hz applied during MEG recording.•Visual stimulus-induced gamma responses assessed during visual detection task.•Retinal control montage ruled out retino-thalamo-cortical stimulation as confound.•TACS phasically suppressed stimulus-induced gamma power and impaired perception.•TACS-induced phasic gamma suppression predicted decline in perceptual performance.