[pymvpa] Hemodynamic lag shift

[Vadim Axel]

Thanks. I will use second one.

With regard ERNiftiDataset: does this class may somehow help to analyze the
ER designs (specifically fast ER), where the data is extremely contaminated
with previous BOLD signal?

2009/4/29 Yaroslav Halchenko <debian at onerussian.com>

> there are a few options you have...
>
> in a block design experiment you can either
> 1. discard volumes on the boundaries of the blocks -- look at
> idsonboundaries
> method of a dataset to figure out which volumes you need to discard
>
> 2. shift labels to account for  the hemodynamic response... lets say
> with TR=2 and desired shift of 6 seconds, just shift labels by 3 and
> discard first 3 volumes... smth like (just typed in... not tested ;))
>
> dataset.labels[3:] = dataset.labels[:-3]
> dataset = dataset.selectSamples(range(3, dataset.nsamples))
>
> 3. use BoxcarMapper mapper to just get a mean activation pattern of the
> block (or simply use that ERNiftiDataset in the fashion similar to
> ER-dataset analysis)
>
>
>
> On Wed, 29 Apr 2009, Vadim Axel wrote:
>
> >    Hi guys,
> >    I wonder whether you are making hemodynamic lag shift in pyMVPA? Here
> >    it the thread, where you discussed this issue with regard to Haxby's
> >    dataset.
> >    [1]
> http://www.mail-archive.com/pkg-exppsy-pymvpa@lists.alioth.debian.or
> >    g/msg00173.html
> >    I think it's a critical procedure, especially when designed consists
> of
> >    short blocks (like 10-15 secs), where you might miss considerable
> >    amount of information. As far as I remember in Princeton MVPA matlab
> >    toolbox such a option existed.
> >    Thaanks,
> >    Vadim
>
> > Ссылки
>
> >    1.
> http://www.mail-archive.com/pkg-exppsy-pymvpa@lists.alioth.debian.org/msg00173.html
>
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>
>
> --
> Yaroslav Halchenko
> Research Assistant, Psychology Department, Rutgers-Newark
> Student  Ph.D. @ CS Dept. NJIT
> Office: (973) 353-1412 | FWD: 82823 | Fax: (973) 353-1171
>        101 Warren Str, Smith Hall, Rm 4-105, Newark NJ 07102
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>
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