Objectives: Event-related potentials (EP) indicate neuronal processes with
a high temporal resolution, while functional magnetic resonance imaging (fM
RI) has a high spatial distribution. Information from both techniques may c
omplement each other. However, this combination is fraught with difficulty
because of a possible interference of the skull or the scalp with scalp-rec
orded EP. The aim of the present study was to investigate this influence of
skull and scalp thicknesses on event-related P300 potentials.
Methods: Thirty healthy controls were examined using an auditory evoked P30
0 elicited by a standard oddball paradigm. Skull and scalp thicknesses were
determined using coronal T2-weighted magnetic resonance imaging (MRI).
Results: P3b-amplitudes were significantly correlated with temporo-parietal
skull thickness (r = -0.42; P = 0.021; regression slope of - 1.14 muV/mm s
kull thickness), whereas scalp had no influence on P300. The amplitude of t
he more frontal subcomponent P3a was not related to frontal skull thickness
.
Conclusions: Therefore, the utility of P300 as a research tool can be enhan
ced when adjustment for skull thickness is made. (C) 2001 Elsevier Science
Ireland Ltd. All rights reserved.