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Brain State-dependent Brain Stimulation with Real-time Electroencephalography-Triggered Transcranial Magnetic Stimulation
Published on: August 20, 2019
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State-dependent brain stimulation: Power or phase?
Fatemeh Khademi1, Vladislav Royter1, Alireza Gharabaghi1
1Division of Functional and Restorative Neurosurgery, and Tuebingen NeuroCampus, Eberhard Karls University Tuebingen, Germany.
Brain Stimulation
|November 4, 2018
Summary
Motor cortex activity influences corticospinal excitability (CSE) through beta oscillations. Beta power increases CSE by 40-70%, while precise phase timing can boost it by 180%.
Area of Science:
- Neuroscience
- Motor Control
- Brain Oscillations
Background:
- Intrinsic motor cortex activity modulates corticospinal excitability (CSE).
- This modulation is linked to beta oscillations (16-17 Hz) in terms of power and phase.
- Understanding these mechanisms is key for brain-computer interfaces and neurorehabilitation.
Purpose of the Study:
- Quantify the impact of beta power and phase on CSE.
- Determine the importance of stimulation timing for input gain.
- Investigate how oscillatory power versus phase influences CSE magnitude.
Main Methods:
- Single-pulse transcranial magnetic stimulation (TMS) applied over the primary motor cortex.
- Simultaneous electroencephalography (EEG) recordings in healthy subjects at rest.
- Corticospinal gain modulation assessed via motor-evoked potential (MEP) amplitude variability.
Main Results:
- Lower beta power significantly increased CSE by 40-70% compared to higher power.
- Phase-dependent modulation, timed to the rising phase of beta oscillations, achieved up to 180% CSE increase.
- Stimulation timing was critical for phase-mediated CSE modulation.
Conclusions:
- Beta oscillation power and phase differentially impact CSE.
- Precise phase-based timing offers a potent mechanism for modulating CSE.
- Findings inform the development of closed-loop, state-dependent stimulation for neurorehabilitation.
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