Christian:
Thanks. With your reply and the melodic _slices, I have more sense about ICA on fMRI now. One more question: Is the number of the independent components controlled by preprocess PCA? There is a parameter that I can modify in MELODIC, threshold. Is that parameter for controlling the summation of eigenvalues in PCA? Thus the number of IC afterwards?
Thanks a lot
Xuelin
****************************************
Xuelin Cui
Department of Electrical Engineering
University of Hawaii-Manoa
Honolulu HI 96822
Tel: 1-808-349-0983
Email: [log in to unmask]
****************************************
----- Original Message -----
From: Christian Beckmann <[log in to unmask]>
Date: Monday, April 30, 2007 4:00 am
Subject: Re: [FSL] a question on IC map and time course
To: [log in to unmask]
> Hi
>
> I do not understand why you start talking about slices - the rest
> is
> bbasically right.
> cheers
> c
>
>
>
>
> On 30 Apr 2007, at 14:50, Xuelin Cui wrote:
>
> > Christian:
> >
> > Thanks for your reply.
> >
> > According to your last Email, can I understand the spatial map
> and
> > the time course for a single component as follows: Those spatial
> > maps of a single IC is aquired at same time, but from different
> > slices. The spatial map of an single IC is for all the time
> points
> > during the scan. The corresponding time course is for controlling
>
> > how the spatial map contribute to the fMRI signal at each time
> points.>
> > Am I right?
> >
> > Thanks a lot
> >
> > Xuelin
> >
> > ****************************************
> > Xuelin Cui
> > Department of Electrical Engineering
> > University of Hawaii-Manoa
> > Honolulu HI 96822
> >
> > Tel: 1-808-349-0983
> > Email: [log in to unmask]
> > ****************************************
> >
> > ----- Original Message -----
> > From: Christian Beckmann <[log in to unmask]>
> > Date: Monday, April 30, 2007 7:53 pm
> > Subject: Re: [FSL] a question on IC map and time course
> > To: [log in to unmask]
> >
> >> Hi,
> >>
> >> On 30 Apr 2007, at 08:54, Xuelin Cui wrote:
> >>
> >>> hi folks:
> >>>
> >>> I ran MELODIC for fMRI data, and thus have a bunch of
> >> independent
> >>> components which are displayed by a html file. In the html file,
> >>
> >>> there is a spatial map, a time course, as well as a Fourier
> >>> spectrum of the time course.
> >>>
> >>> I have some questions on those in the html file:
> >>>
> >>> 1. Are all the spatial maps in single html file snapped at
> >>> different time point? IF so what time are they?
> >>>
> >> No
> >>
> >>> 2. What is the relation between the time course and the spatial
> >> map
> >>> in the same html file?
> >>>
> >>
> >> They express the spatial and temporal characteristics of a
> >> component
> >> - in a similar way that EVs (regressors in the GLM) and the
> >> associated maps of parameter estimates express BOLD modulation.
> >> That
> >> is, the spatial maps corresponds to a map of parameter estimates
> >> and
> >> the time course describes how that spatial map is modulated in
> >> strength at different time points.
> >>
> >>> 3. Are the 125 points time course variance corresponds to a
> >> certain
> >>> voxel in the brain? If so, which voxel is it? If not, what is it
> >>
> >>> related to? Some certain region?
> >>>
> >>
> >> Likewise, the time course is related to the entire IC map - not to
> >> a
> >> single voxel.
> >> cheers
> >> christian
> >>
> >>> Thanks a lot
> >>>
> >>> Xuelin
> >>>
> >>> ****************************************
> >>> Xuelin Cui
> >>> Department of Electrical Engineering
> >>> University of Hawaii-Manoa
> >>> Honolulu HI 96822
> >>>
> >>> Tel: 1-808-349-0983
> >>> Email: [log in to unmask]
> >>> ****************************************
> >>
> >> ____
> >> 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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