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Updated: Feb 22, 2026
Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging
Published on: June 5, 2017
Modulation of Long-Range Connectivity Patterns via Frequency-Specific Stimulation of Human Cortex
Christiane A Weinrich1, John-Stuart Brittain2, Magdalena Nowak3
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Department of Cognitive Neurology and Department of Neurology, University Medical Centre, University of Goettingen, Goettingen 37075, Germany.
Beta oscillations in the motor cortex influence brain communication. Applying beta-frequency transcranial alternating current stimulation (tACS) altered connectivity patterns in the primary motor cortex (M1) without affecting local activity.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Brain Oscillations
Background:
- The phase of local brain oscillations is increasingly recognized for its role in long-range functional connectivity.
- Beta (20 Hz) oscillations are implicated in motor system function.
- The 'communication through coherence' hypothesis suggests oscillation phase synchrony dictates network communication.
Purpose of the Study:
- To investigate if beta-band oscillations support the 'communication through coherence' theory within the human cortical motor network in vivo.
- To examine the effects of transcranial alternating current stimulation (tACS) on local activity and long-range functional connectivity.
Main Methods:
- Combined non-invasive transcranial alternating current stimulation (tACS) with resting-state functional MRI (fMRI).
- Twelve healthy subjects underwent three fMRI scans with 20 Hz, 5 Hz, or sham tACS applied to the primary motor cortex (M1).
- Inter-areal blood-oxygen-level-dependent (BOLD) signal correlation was used as a proxy for communication.
Main Results:
- Beta-frequency tACS significantly altered the connectivity pattern of the stimulated primary motor cortex (M1).
- No significant changes were observed in overall local activity or broader network connectivity.
- A phase-precession model supported the empirical findings and offered emergent predictions.
Conclusions:
- Local beta-frequency oscillations play a role in modulating long-range functional connectivity within the motor cortical network.
- Findings support the 'communication through coherence' hypothesis by demonstrating how local oscillatory activity can influence network communication.
- This research provides insights into the mechanisms by which neural oscillations underpin brain network dynamics.
