Ordinary least squares dipole localization is influenced by the reference.
It is shown empirically, analytically and in simulations that common and average referenced recordings differentially affect the accuracy of equivalent source estimates. This effect is mediated by the influence of the reference on noise correlations. The general conclusion of this analysis is that, if software only allows for ordinary least squares estimation (OLS), then average referencing should be preferred, although these estimates will still be sub-optimal. Optimal estimates are derived by generalized least squares (GLS) which accounts for correlated noise. With GLS, average and common referenced recordings give rise to comparable accuracy.
Huizenga
H M
HM
Department of Developmental Psychology, University of Amsterdam, The Netherlands. op_huizenga@macmail.psy.uva.nl
Molenaar
P C
PC
D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D012015:Reference Standards