Format

Send to:

Choose Destination
See comment in PubMed Commons below
Brain Stimul. 2014 Nov-Dec;7(6):878-89. doi: 10.1016/j.brs.2014.07.033. Epub 2014 Jul 19.

Endogenous cortical oscillations constrain neuromodulation by weak electric fields.

Author information

  • 1Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
  • 2Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
  • 3Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
  • 4Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: flavio_frohlich@med.unc.edu.

Abstract

BACKGROUND:

Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation modality that may modulate cognition by enhancing endogenous neocortical oscillations by application of sine-wave electric fields. Yet, the role of endogenous network activity in enabling and shaping the effects of tACS has remained unclear.

OBJECTIVE:

We combined optogenetic stimulation and multichannel slice electrophysiology to elucidate how the effect of a weak sine-wave electric field depends on the ongoing cortical oscillatory activity. We hypothesized that endogenous cortical oscillations constrain neuromodulation by tACS.

METHODS:

We studied the effect of weak sine-wave electric fields on oscillatory activity in mouse neocortical slices. Optogenetic control of the network activity enabled the generation of in vivo-like cortical oscillations for studying the temporal relationship between network activity and sine-wave electric field stimulation.

RESULTS:

Weak electric fields enhanced endogenous oscillations but failed to induce a frequency shift of the ongoing oscillation for stimulation frequencies that were not matched to the endogenous oscillation. This constraint on the effect of electric field stimulation imposed by endogenous network dynamics was limited to the case of weak electric fields targeting in vivo-like network dynamics. Together, these results suggest that the key mechanism of tACS may be enhancing, but not overriding, intrinsic network dynamics.

CONCLUSION:

Our results contribute to understanding the inconsistent tACS results from human studies and propose that stimulation precisely adjusted in frequency to the endogenous oscillations is key to rational design of non-invasive brain stimulation paradigms.

Copyright © 2014 Elsevier Inc. All rights reserved.

KEYWORDS:

Electric field; Multielectrode array; Optogenetics; Resonance; Transcranial alternating current stimulation; tACS

PMID:
25129402
[PubMed - in process]
PMCID:
PMC4259839
[Available on 2015-11-01]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk