Hi Christopher
On 15 Jul 2008, at 21:01, Christopher Bell wrote:
> I want to make sure I am calculating the frequency bins correctly
> for an
> output of fslpspec. The first volume would be (.5) * 1/total time?
>
> Our data has 177 volumes and a TR of 2 seconds. For instance the first
> volume would be (.5) * 1/354s = 0.001412429 Hz and the last volume
> would be
> (.5) * 1/2s = 0.25 Hz. Is this correct?
Yep!
> I have also created a 176 volume
> data; if the even number makes the calculation easier.
> My second question is about the defl and symm options. I have not
> tried
> running anything with defl yet. What does it do? Is it only for
> individual
> ICA?
The deflation approach extracts one component at a time (as described
in Aapo Hyvaerinen's original work on FastICA - melodic is an
implementation of this approach). In my experience this is far less
robust than the symmetric approach where all components are being
estimated simultaneously, that's why the default option is to use the
symmetric estimation approach.
> I was curious if MELODIC contained a way to concatenate in space
> instead of time for a group analysis?
nope, not in the current release version.
cheers
Christian
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