[Eeglablist] Paper on dipole localization available

[Scott Makeig]

All -

Zeynep Akalin Acar and I have published an in-depth simulation study of the
effects of MR-based vs. template head models on equivalent dipole model
localization (e.g., of ICA components).

It is freely available at:

http://link.springer.com/article/10.1007/s10548-012-0274-6/fulltext.html

*Title*:  Effects of forward model errors on EEG source localization

*Abstract*: Subject-specific four-layer boundary element method (BEM)
> electrical forward head models for four participants, generated from
> magnetic resonance (MR) head images using NFT (www.sccn.ucsd.edu/wiki/NFT),
> were used to simulate electroencephalographic (EEG) scalp potentials at 256
> recorded electrode positions produced by single current dipoles of a 3-D
> grid in brain space. Locations of these dipoles were then estimated using
> gradient descent within five template head models fit to the electrode
> positions. These were: a spherical model, three-layer and four-layer BEM
> head models based on the Montreal Neurological Institute (MNI) template
> head image, and these BEM models warped to the recorded electrode
> positions. Smallest localization errors (4.1–6.2 mm, medians) were obtained
> using the electrode-position warped four-layer BEM models, with largest
> localization errors (~20 mm) for most basal brain locations. When we
> increased the brain-to-skull conductivity ratio assumed in the template
> model scalp projections from the simulated value (25:1) to a higher value
> (80:1) used in earlier studies, the estimated dipole locations moved
> outwards (12.4 mm, median). We also investigated the effects of errors in
> co-registering the electrode positions, of reducing electrode counts, and
> of adding a fifth, isotropic white matter layer to one individual head
> model. Results show that when individual subject MR head images are not
> available to construct subject-specific head models, accurate EEG source
> localization should employ a four- or five-layer BEM template head model
> incorporating an accurate skull conductivity estimate and warped to 64 or
> more accurately 3-D measured and co-registered electrode positions.


-- 
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20130206/dd8cdbec/attachment.html>