PT  - JOURNAL ARTICLE
AU  - Fiene, Marina
AU  - Schwab, Bettina C.
AU  - Misselhorn, Jonas
AU  - Herrmann, Christoph S.
AU  - Schneider, Till R.
AU  - Engel, Andreas K.
TI  - Phase-specific manipulation of neural oscillations by transcranial alternating current stimulation
AID  - 10.1101/579631
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 579631
4099  - http://biorxiv.org/content/early/2019/07/18/579631.short
4100  - http://biorxiv.org/content/early/2019/07/18/579631.full
AB  - Oscillatory phase has been proposed as a key parameter defining the spatiotemporal structure of neural activity. To enhance our understanding of brain rhythms, phase-specific modulation of oscillations by transcranial alternating current stimulation (tACS) emerged as a promising approach. However, the effectiveness of tACS is still critically debated. Here, we investigated the phase-specificity of tACS effects on visually evoked steady state responses (SSRs). We observed that the phase shift between flicker and tACS modulates evoked SSR amplitudes. Neural sources of phase-specific effects were localized in the parieto-occipital cortex within flicker-aligned regions. Importantly, tACS effects were stronger in subjects with weaker locking of neural responses to flicker phase. Overall, our data provide evidence for a phase-specific modulation of oscillations by tACS, since SSR amplitude changes can only result from phase-dependent interactions with applied electric fields. This finding corroborates the physiological efficacy of tACS and highlights its potential for controlled modulations of brain signals.