[FieldTrip] Scale of timeseries for dipoles calculated from leadfields and EEG data

Roisin McMackin mcmackr at tcd.ie
Mon Feb 12 21:46:26 CET 2018

Hi all,

I'm using the method as described in https://mailman.science.ru.
nl/pipermail/fieldtrip/2011-April/003690.html to estimate timeseries of
activity for a number of dipole positions and moments. These were obtained
using ft_dipolefitting to localise EEG recorded event related potentials.
Headmodel (BEM) and sensor (128 electrodes) units are in mm and the EEG
data (data.avg) is in microV, these are used to make the leadfield whose
inverse is used to make weights. The leadfield is not normalised (since the
orientation vector is). The amplitudes of the timeseries I'm getting for
each dipole are in the range of about +/-500 to 5000. Is the timeseries
still in the same units as the input data (i.e. microV, so the timeseries
has milliV range amplitude)? If not how can I calculate the units of the
leadfield, weights and timeseries?

Thanks for any help or suggestions,

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