title: Spatial and temporal resolutions of EEG: Is it really black and white? A scalp current density view.
abstract: Among the different brain imaging techniques, electroencephalography (EEG) is classically considered as having an excellent temporal resolution, but a poor spatial one. Here, we argue that the actual temporal resolution of conventional (scalp potentials) EEG is overestimated, and that volume conduction, the main cause of the poor spatial resolution of EEG, also distorts the recovered time course of the underlying sources at scalp level, and hence degrades the actual temporal resolution of EEG. While Current Source Density (CSD) estimates, through the Surface Laplacian (SL) computation, are well known to dramatically reduce volume conduction effects and hence improve EEG spatial resolution, its positive impact on EEG temporal resolution is much less recognized. In two simulation studies, we first show how volume conduction and reference electrodes distort the scalp potential time course, and how SL transform provides a much better spatio-temporal description. We then exemplify similar effects on two empirical datasets. We show how the time courses of the scalp potentials mis-estimate the latencies of the relevant brain events and that CSD provides a much richer, and much more accurate, view of the spatio-temporal dynamics of brain activity.
authors.affiliation: Aix-Marseille Université, CNRS, LNC UMR 7291, 13331 Marseille, France. Electronic address: boris.burle@univ-amu.fr.
authors.forename: Borís
authors.initials: B
authors.lastname: Burle
authors.affiliation: Aix-Marseille Université, CNRS, LNC UMR 7291, 13331 Marseille, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Spieser
authors.affiliation: SCALab, UMR CNRS 9193, Université de Lille, France.
authors.forename: Clémence
authors.initials: C
authors.lastname: Roger
authors.affiliation: Aix-Marseille Université, CNRS, LNC UMR 7291, 13331 Marseille, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Casini
authors.affiliation: Aix-Marseille Université, CNRS, LNC UMR 7291, 13331 Marseille, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Hasbroucq
authors.affiliation: Aix-Marseille Université, CNRS, LNC UMR 7291, 13331 Marseille, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Vidal
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003198:Computer Simulation; D006801:Humans; D008959:Models, Neurological; D012535:Scalp
keywords: Current Source Density; EEG; Time resolution