[FieldTrip] Query about source/gridpoint size after ft_prepare_sourcemodel

[Ravi Mill]

Many thanks for clarifying that Eelke!

________________________________
From: fieldtrip <fieldtrip-bounces at science.ru.nl> on behalf of Eelke Spaak <e.spaak at donders.ru.nl>
Sent: Tuesday, July 24, 2018 3:16:06 AM
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Query about source/gridpoint size after ft_prepare_sourcemodel

Hi Ravi,

Beamforming will estimate source activity at *point* sources; in other
words, the grid points have no spatial extent (i.e., they are
zero-dimensional).

> If so, is the only way to extract 'larger' sources to fit a
> whole-brain grid (e.g. using the 4mm-spaced source template provided by FT),
> identify gridpoints after ft_sourceanalysis that fall within a specified
> Euclidean distance (e.g. 5mm) of the functional atlas MNI coordinates, and
> then e.g. average over all those gridpoints?

Yes, that is definitely a valid approach. You will probably not need
to use such a finely spaced grid if you end up averaging over grid
points anyway. Typically, the spatial filters for neighbouring grid
points will be highly correlated.

Best,
Eelke

>
>
> Thanks in advance!
>
> Ravi
>
>
> --
> Ravi Mill, PhD
> Post-doctoral researcher
> Center for Molecular and Behavioral Neuroscience (CMBN)
> Rutgers University
>
>
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