Hi Steve,
Thanks for your response and your patience!
I understand why I have fractions of TRs as time points. What I am
trying to understand is how I get these values. Can you clarify what is
the positive-going zero crossing that is taken as the onset of the
event? Is it the model curve computed for each trial separately, or
something else?
Thanks again
Stephane
Stephen Smith wrote:
> Hi. The exact timing of the beginning of each event is identified in a high temporal resolution
> version of the model (before it gets sampled at the TR temporal resolution). The timing of the rest
> of the event's "window" is relative to this beginning point, for the purposes of the peristimulus
> plotting. When this beginning falls between TRs, the timing of data, fitted model etc are still
> calculated all relative to this, hence why you see fractional timing values in the x-axis of the plots.
>
> I'm not sure this answers your question, hopefully it helps.
>
> Cheers, Steve.
>
>
>
> On Fri, 19 Jan 2007 12:41:20 -0800, Stephane Jacobs <[log in to unmask]> wrote:
>
>
>>> That's right, to be exact, the exact timing of the positive-going
>>> zero crossing associated with the event, after HRF convolution.
>>>
>> In my case, the timing value for the first TR for each event can be
>> either 0, 0.2, 05 or 0.8 TR. There are 6 occurences of each, which
>> corresponds to the distribution of the oversampling interval across my
>> trials: 6 trials had either 0, 500, 1000 or 1500ms delay between the
>> beginning of the TR and the onset of the event. I just don't understand
>> how the timing information of the raw data text file is related to this
>> delay. Could you clarify this?
>>
>> Thanks a lot again, your help is very much appreciated.
>>
>> Stephane
>>
>>
>>
>>
>> On Wed, Jan 10, 2007 at 04:49:27PM +0000, Steve Smith wrote:
>>
>>> Hi,
>>>
>>> Some of this is covered in the manual at:
>>> http://www.fmrib.ox.ac.uk/fsl/feat5/output.html
>>>
>>> The order of the rows in a ps_tsplot_zstat*_ev*.txt text file should
>>> be - for each event (in the order they are entered in the original
>>> design), a set of rows, one for each TR within the peristimulus
>>> period following the onset of that event.
>>>
>>> That's right, to be exact, the exact timing of the positive-going
>>> zero crossing associated with the event, after HRF convolution.
>>>
>>>
>>> Cheers, Steve.
>>>
>>>
>>> On 8 Jan 2007, at 19:27, Stephane Jacobs wrote:
>>>
>>>
>>>> Hi all,
>>>>
>>>> I'd like to know how events are ordered in the raw data text file
>>>> corresponding to the peristimulus plots created by featquery. i.e.,
>>>> should
>>>> they be ordered in the same way they occurred and are reported in
>>>> the Ev
>>>> file fed into FEAT? Because it's not the case for me...
>>>>
>>>> Also, the time indicated in the first column is based on the onset
>>>> of each
>>>> event, right? Just to check...
>>>>
>>>> Thanks a lot,
>>>>
>>>> Stephane
>>>>
>>> ------------------------------------------------------------------------
>>> ---
>>> Stephen M. Smith, Professor of Biomedical Engineering
>>> Associate Director, Oxford University FMRIB Centre
>>>
>>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>>> +44 (0) 1865 222726 (fax 222717)
>>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>>> ------------------------------------------------------------------------
>>> ---
>>>
>>>
>> ===========================================================
>>
> ==============
>
>
>
--
Stephane Jacobs
Human Neuroimaging and Transcranial Stimulation Lab
36 Straub Hall, 1227 University of Oregon
Eugene, OR 97403 - USA
Email: [log in to unmask]
Tel: (1) 541-346-4184
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