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Published on: September 28, 2018
Is sham cTBS real cTBS? The effect on EEG dynamics
Alexander Opitz1, Wynn Legon2, Jerel Mueller3
1Department of Clinical Neurophysiology, Georg-August-University Göttingen, Germany ; Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA ; Center for the Developing Brain, Child Mind Institute New York, NY, USA.
Even sham transcranial magnetic stimulation (TMS) can impact brain activity. Weak electric fields from sham cTBS altered neural circuits, affecting somatosensory evoked potentials and brain wave phase coupling.
Area of Science:
- Neuroscience
- Electrophysiology
- Brain Stimulation
Background:
- Modern tools enable studying subtle electric stimulation effects on neural populations.
- Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique.
Purpose of the Study:
- To investigate the effects of sham continuous theta burst (cTBS) transcranial magnetic stimulation (TMS) on somatosensory evoked potentials (SEP) and frontal-parietal phase coupling.
- To determine if weak electric fields from sham TMS can influence neural circuits.
Main Methods:
- Sham cTBS TMS applied to the left dorsolateral prefrontal cortex (DLPFC).
- Measurement of somatosensory evoked potentials (SEP) and frontal-parietal phase coupling in alpha and beta bands.
- Comparison of sham TMS (approx. 5% electric field amplitude of real TMS) with real TMS effects.
Main Results:
- Both real and sham cTBS reduced the amplitude of the frontal P14-N30 SEP.
- Both real and sham cTBS increased local phase coupling in the alpha-beta frequency bands of the left frontal cortex.
- Both sham and real cTBS increased frontal-parietal phase coupling and parietal P50-N70 complex amplitude.
Conclusions:
- Weak electric fields generated by sham cTBS TMS can modulate local and downstream neuronal circuits.
- Sham TMS effects on neural circuits differ from those of high-strength TMS.
- These findings highlight the sensitivity of neural circuits to electric fields.
