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<p>Dear Cecilia and Tom,<br>
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<p>I am in a similar situation to the one described by Cecilia, so I thought of asking you for a suggestion.<br>
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<p><br>
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<p>I have a dataset locked to the onset of the cue, and I would like to use the same baseline I used in this dataset to baseline-correct also the same dataset locked to the onset of the target.<br>
</p>
<p><br>
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<p>I tried the solution Tom suggested, but it is not working for me. The reason is that I preprocessed the cue-locked and target-locked datasets separately, therefore they end up having a slightly different number of trials. Do you have any idea of how this
could be solved? Would it make sense to baseline-correct at the grandaverage level?<br>
</p>
<p><br>
</p>
<p>Another option I have been thinking about is to use ft_redefinetrial. In this case I have other problems, though. If I try to use the ft_redefinetrial function after preprocessing and cleaning my cue-locked dataset, it will output all the trials in the raw
data (therefore not accounting for the trial rejection I performed on the cue-locked dataset). Is this the right way to use this function or am I missing something?<br>
</p>
<p><br>
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<p>Thanks in advance for any input and sorry if my question is not very clear (still a newbie!)<br>
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<p><br>
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<p>Best,<br>
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<p>Silvia<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> fieldtrip <fieldtrip-bounces@science.ru.nl> on behalf of Tom Marshall <tom.marshall@psy.ox.ac.uk><br>
<b>Sent:</b> 02 November 2018 23:29<br>
<b>To:</b> FieldTrip discussion list<br>
<b>Subject:</b> Re: [FieldTrip] baseline correcting data with baseline coming from a different grandaverage</font>
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<p style="margin-top:0; margin-bottom:0">Hey Cecilia,</p>
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<p style="margin-top:0; margin-bottom:0">I guess you could do that with a combination of 'ft_selectdata', and 'ft_math'.</p>
<p style="margin-top:0; margin-bottom:0"><br>
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<p style="margin-top:0; margin-bottom:0">Let's say you have datasets called 'stimlocked' and 'cuelocked'</p>
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<p style="margin-top:0; margin-bottom:0">You'd do something like:</p>
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<p style="margin-top:0; margin-bottom:0">% cut out baseline from cuelocked<br>
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<p style="margin-top:0; margin-bottom:0">cfg = [];</p>
<p style="margin-top:0; margin-bottom:0">cfg.latency = [-0.5 0]; % or whatever your baseline window is</p>
<p style="margin-top:0; margin-bottom:0">baseline = ft_selectdata(cfg, cuelocked);</p>
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">% subtract baseline from stimlocked</p>
<p style="margin-top:0; margin-bottom:0">cfg = [];</p>
<p style="margin-top:0; margin-bottom:0">cfg.operation = 'subtract';</p>
<p style="margin-top:0; margin-bottom:0">baseline_corrected_stimlocked = ft_math(cfg, stimlocked, baseline);</p>
<p style="margin-top:0; margin-bottom:0"><br>
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<p style="margin-top:0; margin-bottom:0">I <i>think</i> that ft_math allows you to input algebraic expressions too. So if you wanted to do, for example, a 'relchange' baseline correction you should substitute (something like)</p>
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<p style="margin-top:0; margin-bottom:0">cfg.operation = '(x1-x2)/x2';<br>
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<p style="margin-top:0; margin-bottom:0">Best,</p>
<p style="margin-top:0; margin-bottom:0">Tom<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> fieldtrip <fieldtrip-bounces@science.ru.nl> on behalf of Mazzetti, C. (Cecilia) <C.Mazzetti@donders.ru.nl><br>
<b>Sent:</b> 01 November 2018 11:04:23<br>
<b>To:</b> fieldtrip@science.ru.nl<br>
<b>Subject:</b> [FieldTrip] baseline correcting data with baseline coming from a different grandaverage</font>
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<p>Dear everyone,<br>
</p>
<p>I have some stimulus locked data which I have to baseline with respect to the same data but cue locked.<br>
</p>
<p>I was wondering whether there is a setting in fieldtrip which allows to do that (i.e. set the baseline timw window according to a different dataset, the cue-locked data) and applying it to the stimulus locked data.<br>
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<p>Thanks in advance!<br>
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<font face="arial,sans-serif"><font face="arial,helvetica,sans-serif">Best,</font></font></div>
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<font face="arial,sans-serif"><font face="arial,helvetica,sans-serif">Cecilia</font></font></div>
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<font face="arial,sans-serif"><font face="arial,helvetica,sans-serif"><b>Cecilia Mazzetti - </b></font><font face="arial,helvetica,sans-serif"><b>Ph.D. Candidate </b></font></font></div>
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<span style="font-family:arial,helvetica,sans-serif">Donders Centre for Cognitive Neuroimaging, room 0.068 </span></div>
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