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Spatial enhancement of EEG traces by surface Laplacian estimation: comparison between local and global methods


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Tandonnet, C, Burle, B, Hasbroucq, T and Vidal, F 2005 , 'Spatial enhancement of EEG traces by surface Laplacian estimation: comparison between local and global methods' , Clinical Neurophysiology, vol. 116 , pp. 18-24 , doi: 10.1016/j.clinph.2004.07.021.

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Objective: Surface Laplacian estimation enhances EEG spatial resolution. In this paper, we compare, on empirical grounds, two
computationally different estimations of the surface Laplacian.
Methods: Surface Laplacian was estimated from the same monopolar data set with both Hjorth’s method [local; Electroenceph Clin
Neurophysiol 39 (1975) 526] as modified by MacKay [Electroenceph Clin Neurophysiol 56 (1983) 696] and with spherical spline
interpolation [global; Electroenceph Clin Neurophysiol 72 (1989) 184].
Results: The grand averages computed with the two methods proved to be very similar but differed markedly from the monopolar ones.
The two different computations were highly correlated, presented low relative errors and allowed to evidence comparable experimental
Conclusions: These results suggest that Hjorth’s method and spherical spline interpolation convey similar topographic and chronometric
Significance: We provide empirical evidence that local and global methods of surface Laplacian estimation are equivalent to improve the
spatial resolution of EEG traces. Global methods allow to explore the scalp topography and local methods allow to spare time in electrode
setting that can be useful for studies on special populations (i.e. children, aged subjects) and for clinical purposes.

Item Type: Article
Authors/Creators:Tandonnet, C and Burle, B and Hasbroucq, T and Vidal, F
Keywords: ERP; Scalp current density; Current source density; Source derivation; Clinical applications
Journal or Publication Title: Clinical Neurophysiology
ISSN: 1388-2457
DOI / ID Number: 10.1016/j.clinph.2004.07.021
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