![]() We can observe these high frequency artifacts with the naked eye. Why it affects EEG: That electrical activity produced by the muscles can interfere with the actual EEG activity.This activity can be measured and the resulting signal is called electromyography (EMG). Origin: Muscles produce electrical activity when they are contracted.Effect on frequency domain: Effect in low frequencies that can be confused with delta and theta bands.In general the artifact amplitude of the artifact is almost proportional to the angle of gaze. Lateral movements of the eye affect also the frontal areas but are more significant the closer to the temples. Effect on time-domain: Blinking produces a quick change with high amplitude on the EEG signals in the electrodes of the frontal area, more pronounced in those closer to the eyes.Types of effects: Blinking, lateral movement, eye movements.Why it affects EEG: This distortion is known as the EOG (Electrooculogram) signal and has an amplitude usually one order of magnitude larger than the EEG signal, reaching values around 100-200 microvolts.Origin: The eye can be electrically modeled as a magnetic dipole and it distorts the electric field in the region when it moves. ![]() Independent components were extracted using logistic infomax ICA algorithm ( Bell & Sejnowski, 1995). The EEG device used to create most of the figures showing the artifacts was collected with the Bitbrain EEG versatile 16ch system, band pass filtered between 0.5 and 30 Hz.
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