On this same note, I was wondering if you would recommend denoising each
subject prior to concatenating the data and running melodic? Thanks.
On 12 Jul 2007, Peter Fried wrote:
> One quick follow-up: Should I use the automatic dim estimate when running
> melodic on the group-wise concatenated data, or will that give me hundreds
> of components? Thanks
>
> -Pete
>
> > Hi
> >
> > yes, this is what I' expect - data sets with increased amount of head
> > motion will typically have an increased model order. Estimating more
> > components in those data sets is useful as these additional
> > components soak up variability due to uninteresting but existing head
> > motion effects. As such fixing the number of components to 30 does
> > sound sub-optimal.
> > cheers
> > christian
> >
> >
> >
> > On 12 Jul 2007, at 14:31, Peter Fried wrote:
> >
> >> I've noticed that letting MELODIC estimate the number of components
> >> somewhat decreases the amount of noise found in resting-state
> >> networks.
> >> It also seems to break some RSNs into multiple components. We had been
> >> selecting 30 components but with the automatic dim estimate the
> >> numbers
> >> are in the 40-50 range (depending ususally on how much motion there
> >> is).
> >> Thanks.
> >>
> >> -Pete
> >>
> >>> Hi,
> >>>
> >>> no, it does not matter if some inputs have different number of
> >>> components. I always think that the automatic dim estimate is what
> >>> should be used - are numbers very much hgher than 30?
> >>> cheers
> >>> c
> >>>
> >>>
> >>> On 11 Jul 2007, at 21:05, Peter Fried wrote:
> >>>
> >>>> Hi All,
> >>>>
> >>>> If I am merging the Melodic outputs for multiple subjects in
> >>>> order to
> >>>> rerun Melodic, do all the inputs have to have the same number of
> >>>> components?
> >>>>
> >>>> I am trying to decide between choosing 30 components for each
> >>>> subject (180
> >>>> volumes, TR=2.0) or letting Melodic estimate the number.
> >>>>
> >>>> Thanks.
> >>>>
> >>>> -Pete
> >>>
> >>> ____
> >>> Christian F. Beckmann
> >>> University Research Lecturer
> >>> Oxford University Centre for Functional MRI of the Brain (FMRIB)
> >>> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
> >>> [log in to unmask] http://www.fmrib.ox.ac.uk/~beckmann
> >>> tel: +44 1865 222551 fax: +44 1865 222717
> >>>
> >
> > ____
> > Christian F. Beckmann
> > University Research Lecturer
> > Oxford University Centre for Functional MRI of the Brain (FMRIB)
> > John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
> > [log in to unmask] http://www.fmrib.ox.ac.uk/~beckmann
> > tel: +44 1865 222551 fax: +44 1865 222717
> >
>
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