Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration

Proc Natl Acad Sci U S A. 2021 Feb 16;118(7):e2015488118. doi: 10.1073/pnas.2015488118.


Brain connectivity plays a major role in the encoding, transfer, and integration of sensory information. Interregional synchronization of neural oscillations in the γ-frequency band has been suggested as a key mechanism underlying perceptual integration. In a recent study, we found evidence for this hypothesis showing that the modulation of interhemispheric oscillatory synchrony by means of bihemispheric high-density transcranial alternating current stimulation (HD-TACS) affects binaural integration of dichotic acoustic features. Here, we aimed to establish a direct link between oscillatory synchrony, effective brain connectivity, and binaural integration. We experimentally manipulated oscillatory synchrony (using bihemispheric γ-TACS with different interhemispheric phase lags) and assessed the effect on effective brain connectivity and binaural integration (as measured with functional MRI and a dichotic listening task, respectively). We found that TACS reduced intrahemispheric connectivity within the auditory cortices and antiphase (interhemispheric phase lag 180°) TACS modulated connectivity between the two auditory cortices. Importantly, the changes in intra- and interhemispheric connectivity induced by TACS were correlated with changes in perceptual integration. Our results indicate that γ-band synchronization between the two auditory cortices plays a functional role in binaural integration, supporting the proposed role of interregional oscillatory synchrony in perceptual integration.

Keywords: dichotic listening; dynamic causal modeling; fMRI; speech perception; transcranial alternating current stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Auditory Perception*
  • Brain / physiology*
  • Connectome
  • Female
  • Functional Laterality*
  • Gamma Rhythm
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Transcranial Direct Current Stimulation
  • Young Adult