The effects of ocular artifacts on (lateralized) broadband power in the EEG.
OBJECTIVE
Empirical evidence suggests that blinks and eye movements do not generate substantial activity outside the delta and theta range, and that the propagation of ocular activity to the EEG is rather symmetrical. These observations suggest that an alteration of the alpha and beta asymmetry of the EEG due to ocular artifacts is not likely to occur. The aim of the present study is to examine the effects of ocular artifacts on broadband EEG parameters.


METHODS
EEG and EOG were recorded from 31 participants in a resting condition with eyes open and closed, allowing for spontaneous ocular activity. General effects of ocular artifacts were examined with mean comparisons, and differential effects were examined with correlation analysis of data portions that were selected for a presence or absence of artifacts.


RESULTS
At single sites, blinks and eye movements exerted substantial general effects on the whole EEG spectrum, but there were no substantial differential effects of artifacts in the alpha and beta bands, except at the frontopolar sites. The distorting effects of ocular artifacts were smaller in magnitude for asymmetry than for single site measures.


CONCLUSIONS
The control of ocular artifacts may be dispensable for correlation analyses of alpha or beta band parameters.
Hagemann
D
D
Laboratory of Personality and Cognition, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, MD, Baltimore 21224, USA. hagemann@lpc.grc.nia.nih.gov
Naumann
E
E
D000328:Adult; D000704:Analysis of Variance; D016477:Artifacts; D001767:Blinking / Q000502:physiology; D004569:Electroencephalography; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology; D005143:Eyelids / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009799:Ocular Physiological Phenomena