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Physiological processes non-linearly affect electrophysiological recordings during transcranial electric stimulation
Nima Noury1, Joerg F Hipp2, Markus Siegel3
1Centre for Integrative Neuroscience & MEG Center, University of Tübingen, Germany; IMPRS for Cognitive and Systems Neuroscience, Tübingen, Germany.
Neuroimage
|April 5, 2016
Summary
Non-linear artifacts in transcranial electric stimulation (tES) EEG/MEG data arise from physiological processes, not just currents. Current methods fail to remove these complex artifacts, which can be mistaken for neural activity.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Signal Processing
Background:
- Transcranial electric stimulation (tES) non-invasively modulates human brain activity.
- Simultaneous EEG/MEG recordings with tES are challenging due to stimulation artifacts.
- Existing artifact removal techniques may be insufficient for complex tES-induced artifacts.
Purpose of the Study:
- To investigate the nature of stimulation artifacts in EEG and MEG during tES.
- To determine if physiological factors modulate tES artifacts.
- To evaluate the effectiveness of current artifact rejection methods.
Main Methods:
- EEG and MEG recordings during transcranial alternating current stimulation (tACS) and transcranial direct current stimulation (tDCS).
- Analysis of artifact modulation by physiological signals (heartbeat, respiration).
- Comparison of artifact characteristics with standard artifact rejection methods.
Main Results:
- tES artifacts are non-linearly modulated by heartbeat and respiration, independent of stimulation frequency.
- Standard artifact rejection methods do not fully remove these physiological modulations.
- Non-linear artifacts can be misinterpreted as neural entrainment.
Conclusions:
- tES artifacts are complex and influenced by physiological states.
- Current artifact removal techniques are inadequate for tES-EEG/MEG studies.
- New methods are needed to accurately remove non-linear tES artifacts.
