[FieldTrip] a .mat file about meg data do preprocessing

["Jörn M. Horschig"]

Dear Xiao,

Somehow your channel names seem to not be recognized by FieldTrip, and 
then it reverts to default channel names (chan001, chan002, ...). You 
will see that data_org.label will have those channel labels. 
Subsequently, you define in the cfg for timelockanalysis channel names 
that are not in your data (your channels are called chanXXX, not MEGXXXX 
now), and FieldTrip thus does not perform the operation on any channel.
I don't know much about EEGLAB and how it is integrated with FieldTrip - 
there should be an eeglab2fieldtrip function though in 
fieldtrip/external/eeglab. Maybe you can try this, or maybe someone else 
here knows why your channel labels do not get copied over to FieldTrip 
correctly.

Good luck :)
Best,
Jörn

On 5/18/2013 4:06 PM, ?? wrote:
> Dear all,
> I have a .mat file about meg data(102*98800,channel*time,channel is 
> 'MEG0111','MEG0121'.....'M*1' );
> Then I use eeglab read it,got .set file;I want use ft_timelockanalysis 
> then
> /cfg = [];
> cfg.dataset     = 'megalpha.set';
> cfg.grad=grad;
> data_org        = ft_preprocessing(cfg)/
> >grad =
>      chanori: [102x3 double]
>      chanpos: [102x3 double]
>     chantype: {102x1 cell}
>     chanunit: {102x1 cell}
>      coilori: [510x3 double]
>      coilpos: [510x3 double]
>        label: {102x1 cell}
>          tra: [102x510 double]
>         unit: 'cm'
> Warning: creating default channel names
> > In fileio\private\read_eeglabheader at 53
>   In ft_read_header at 572
>   In ft_preprocessing at 343
> processing channel { 'chan001' 'chan002' 'chan003' 'chan004' 'chan005' 
> 'chan006' 'chan007' 'chan008' 'chan009' 'chan010' 'chan011' 'chan012' 
> 'chan013' 'chan014' 'chan015' 'chan016' 'chan017' 'chan018' 'chan019' 
> 'chan020' 'chan021' 'chan022' 'chan023' 'chan024' 'chan025' 'chan026' 
> 'chan027' 'chan028' 'chan029' 'chan030' 'chan031' 'chan032' 'chan033' 
> 'chan034' 'chan035' 'chan036' 'chan037' 'chan038' 'chan039' 'chan040' 
> 'chan041' 'chan042' 'chan043' 'chan044' 'chan045' 'chan046' 'chan047' 
> 'chan048' 'chan049' 'chan050' 'chan051' 'chan052' 'chan053' 'chan054' 
> 'chan055' 'chan056' 'chan057' 'chan058' 'chan059' 'chan060' 'chan061' 
> 'chan062' 'chan063' 'chan064' 'chan065' 'chan066' 'chan067' 'chan068' 
> 'chan069' 'chan070' 'chan071' 'chan072' 'chan073' 'chan074' 'chan075' 
> 'chan076' 'chan077' 'chan078' 'chan079' 'chan080' 'chan081' 'chan082' 
> 'chan083' 'chan084' 'chan085' 'chan086' 'chan087' 'chan088' 'chan089' 
> 'chan090' 'chan091' 'chan092' 'chan093' 'chan094' 'chan095' 'chan096' 
> 'chan097' 'chan098' 'chan099' 'chan100' 'chan101' 'chan102' }
> reading and preprocessing
> reading and preprocessing trial 1 from 1
> data_org =
>            hdr: [1x1 struct]
>          label: {102x1 cell}
>           time: {[1x98800 double]}
>          trial: {[102x98800 double]}
>        fsample: 1037
>     sampleinfo: [1 98800]
>            cfg: [1x1 struct]
> /cfg                   = [];
> cfg.covariance        = 'yes';
> cfg.channel           = 'M*1';
> cfg.vartrllength      = 2;
> cfg.covariancewindow  = 'all';
> timelock              = ft_timelockanalysis(cfg, data_org);/
> timelock =
>        avg: [0x98800 double]
>        var: [0x98800 double]
>       time: [1x98800 double]
>        dof: [0x98800 double]
>      label: {0x1 cell}
>     dimord: 'chan_time'
>        cov: []
>        cfg: [1x1 struct]
> there is no error displyed in command window but the timlock is empty,why?
> thanks for you help,
> best,
> xiao
>
>
> _______________________________________________
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> fieldtrip at donders.ru.nl
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-- 
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team

P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

Contact:
E-Mail: jm.horschig at donders.ru.nl
Tel:    +31-(0)24-36-68493
Web: http://www.ru.nl/donders

Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands

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