[FieldTrip] FT_SCALPCURRENTDENSITY options and elec units

Akiko Ikkai akiko.ikkai at gmail.com
Fri Aug 31 21:59:00 CEST 2012


I'm trying to run plv analysis, first acquiring SCD of my data with
ft_scalcurrentdensity, and am confused about the difference between
cfg.method = 'finite' and 'spline.'  Both gave similar results short-range,
but 'spline' gives higher plv at long range plv. I'd love it if someone
could explain or suggest reading on the difference between these two
methods (or is one method preferred over the other in some cases?).

Also, I'm not sure whether or not I should convert my elec.pnt  values,
since the code ft_scalcurrentdensity says that
"Note that the skin conductivity, electrode dimensions and the potential all
have to be expressed in the same SI units." My elec.pnt are in cm, and I'm
using the default conductivity (0.33 S/m). Do I need to do something like
elec.pnt = elec.pnt/100 to convert the unit from cm to m? With or without
conversion, I got the same results (viewed with ft_topoplotTFR), and I'm a
little confused... Thank you in advance for your time! Akiko

Akiko Ikkai, Ph.D.
Postdoctoral Fellow
Department of Psychological and Brain Sciences
Johns Hopkins University
Ames Hall, 3400 N. Charles St.
Baltimore, MD 21218
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