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Bilateral Gamma/Delta Transcranial Alternating Current Stimulation Affects Interhemispheric Speech Sound Integration

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Preisig Basil C., Sjerps Matthias J., Hervais-Adelman Alexis, Kösem Anne, Hagoort Peter, Riecke Lars,
Project Exploring audio-motor integration: a novel approach to overcoming hearing impairment
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Original article (peer-reviewed)

Journal Journal of Cognitive Neuroscience
Page(s) 1 - 9
Title of proceedings Journal of Cognitive Neuroscience
DOI 10.1162/jocn_a_01498

Open Access

Type of Open Access Green OA Embargo (Freely available via Repository after an embargo)


Perceiving speech requires the integration of different speech cues, that is, formants. When the speech signal is split so that different cues are presented to the right and left ear (dichotic listening), comprehension requires the integration of binaural information. Based on prior electrophysiological evidence, we hypothesized that the integration of dichotically presented speech cues is enabled by interhemispheric phase synchronization between primary and secondary auditory cortex in the gamma frequency band. We tested this hypothesis by applying transcranial alternating current stimulation (TACS) bilaterally above the superior temporal lobe to induce or disrupt interhemispheric gamma-phase coupling. In contrast to initial predictions, we found that gamma TACS applied in-phase above the two hemispheres (interhemispheric lag 0°) perturbs interhemispheric integration of speech cues, possibly because the applied stimulation perturbs an inherent phase lag between the left and right auditory cortex. We also observed this disruptive effect when applying antiphasic delta TACS (interhemispheric lag 180°). We conclude that interhemispheric phase coupling plays a functional role in interhemispheric speech integration. The direction of this effect may depend on the stimulation frequency.