Selective modulation of interhemispheric functional connectivity by HD-tACS shapes perception

PLoS Biol. 2014 Dec 30;12(12):e1002031. doi: 10.1371/journal.pbio.1002031. eCollection 2014 Dec.

Abstract

Oscillatory neuronal synchronization between cortical areas has been suggested to constitute a flexible mechanism to coordinate information flow in the human cerebral cortex. However, it remains unclear whether synchronized neuronal activity merely represents an epiphenomenon or whether it is causally involved in the selective gating of information. Here, we combined bilateral high-density transcranial alternating current stimulation (HD-tACS) at 40 Hz with simultaneous electroencephalographic (EEG) recordings to study immediate electrophysiological effects during the selective entrainment of oscillatory gamma-band signatures. We found that interhemispheric functional connectivity was modulated in a predictable, phase-specific way: In-phase stimulation enhanced synchronization, anti-phase stimulation impaired functional coupling. Perceptual correlates of these connectivity changes were found in an ambiguous motion task, which strongly support the functional relevance of long-range neuronal coupling. Additionally, our results revealed a decrease in oscillatory alpha power in response to the entrainment of gamma band signatures. This finding provides causal evidence for the antagonistic role of alpha and gamma oscillations in the parieto-occipital cortex and confirms that the observed gamma band modulations were physiological in nature. Our results demonstrate that synchronized cortical network activity across several spatiotemporal scales is essential for conscious perception and cognition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Behavior
  • Cerebrum / physiology*
  • Cortical Synchronization
  • Electrodes
  • Female
  • Gamma Rhythm / physiology
  • Humans
  • Male
  • Motion Perception / physiology*
  • Nerve Net / physiology*
  • Stroboscopy
  • Transcranial Direct Current Stimulation*

Associated data

  • Dryad/10.5061/dryad.B0R5Q

Grant support

This work was supported by grants from the European Union (ERC-2010-AdG-269716, AKE; http://erc.europa.eu/), the German Research Foundation (SFB936/A3/Z1, AKE; RA2357/1-1, SR and DS; SFB/TRR 31, CSH; SPP1665 EN 533/13-1, AKE; and SPP1665 HE 3353/8-1, CSH; http://www.dfg.de), and the German National Academic Foundation (RFH; http://www.studienstiftung.de/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.