Comparison of two methods for correcting ocular artefacts in EEGs

Abstract

A major problem in the study of brain potentials is the occurrence of ocular artefacts in electro-encephalograms. OAs can be monitored by placing electrodes near the eyes and recording electro-oculograms. In the paper, two OA correction methods based on simulations are compared; the Jervis method and the vandenBerg method. In most simulations, the residual (the difference between the original EEG and the EEG after correction) is smaller in amplitude and variance for the vandenBerg method than for the Jervis method. When eye movements and blinks are given different factors, the blinks are not removed completely. For both methods, the residual of the blinks increases with the differences between the model parameters for the blinks and for eye movements. The occurrence of a slow negative wave greatly disturbs the estimated parameters and thus the residuals of the Jervis method. For the vandenBerg method, there is only a very small effect. The conclusion from correcting a recorded data set, which does not contain a slow negative wave, is that, for these data, there is no evidence that one method is better than the other.

EOG correction: A comparison of four methods

“…While improving matters through rigorous quantification, such methods are limited by the correlation that would also result from residual EOG in the EEG channels, and so this approach to validation is not appropriate. Some studies attempt to overcome this difficulty by employing simulations whereby a model EEG is created/simulated and thus the adequacy of correction algorithms is assessed by comparing the corrected to the model EEG (e.g., Croft & Barry, 1998b, 2000c; van den Berg‐Lenssen, van Gisbergen, & Jervis, 1994). However, such tests are based on a number of assumptions that are themselves in need of determination.…”

Computerized processing of EEG–EOG–EMG artifacts for multi-centric studies in EEG oscillations and event-related potentials

“…Frequency domain correction (FREQ) has been previously described in detail (Van den Berg-Lenssen et al, 1994). In the set of single trials, we selected five 256-sampled intervals on EEG and EOG channels, based on the minimum and the maximum EOG amplitude.…”