Correction of muscle artefacts in the EEG power spectrum.
OBJECTIVE
To provide a method for correcting muscle artefacts in fast band power at EEG derivations.


METHODS
We define an indicator of surface EMG as power in the band 51.0-69.0 Hz ('muscle power'). This indicator is used to approximately eliminate the contribution of muscle activity on fast band power via a regression model.


RESULTS
(1) Patients show a larger proportion of muscle activity in fast band power. (2) There is a clear topographic pattern, frontal-temporal derivations being most susceptible to EMG artefacts. (3) The contribution of surface EMG can be drastically reduced by the proposed correction method. (4) Without correction, results for fast bands can be biased when e.g. comparing control and patient groups and the proposed correction method by and large eliminates this bias.


CONCLUSIONS
It is advisable to correct the quantitative EEG reflecting fast activity for the extent of EMG artefacts.


CONCLUSIONS
To render the quantitative EEG more valid as an indicator of cerebral activity.
Gasser
Theo
T
Department Biostatistics, Institute for Social and Preventive Medicine, University of Zurich, Sumatrastr. 30, CH-8006 Zürich, Switzerland. tgasser@ifspm.unizh.ch
Schuller
Jan C
JC
Gasser
Ursula Schreiter
US
D000368:Aged; D000513:Alpha Rhythm; D000544:Alzheimer Disease / Q000503:physiopathology; D016477:Artifacts; D001611:Beta Rhythm; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004576:Electromyography; D005583:Fourier Analysis; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D012044:Regression Analysis; D015203:Reproducibility of Results