[FieldTrip] Beamformer for S1 A1 responses with EEG

[Maris Skujevskis]

Dear Fieldtrip community,

I am working on localizing primary sensory responses using the beamformer
technique. My subjects receive 'noisy' stimuli: tactile vibrations (0-100Hz
frequncy content) to both index fingers, OR 1-2kHz auditory noise stimuli
in both ears for 500 ms; I have 118 EEG channels and around 170 clean
trials for each modality per subject to work with. My results look ok at
the sensor level, but the sources look messy (for now...).

My question is: how accurately have you managed to
beamformer-source-localize primary somatosensory/auditory responses - say,
in a range from "not at all", "very vaguely/unreliably", "reasonably",
"quite accurately"?

I just want to know how successful you guys have been so I know what to
expect from EEG data, when to feel satisfied with the result I am getting.

Thanks a lot for your input!





On Wednesday, July 27, 2016, <fieldtrip-request at science.ru.nl> wrote:

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>    1. ft_databrowser error (Carmen Kung)
>
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 27 Jul 2016 16:01:40 +1000
> From: Carmen Kung <carmen.kung at mq.edu.au <javascript:;>>
> To: <fieldtrip at science.ru.nl <javascript:;>>
> Subject: [FieldTrip] ft_databrowser error
> Message-ID: <d5ef871e-c3f5-fae8-4bcd-96e67d3fde96 at mq.edu.au <javascript:;>
> >
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Dear fieldtripers,
>
> After running ft_definetrial and ft_preprocessing, we try to plot the
> data using ft_databrowser using the script at follow:
>
>
>  >> cfg = [];
>  >> ft_databrowser(cfg, data);
>
> But this is the error message we got:
>
> the input is raw data with 69 channels and 25 trials
> detected   0 visual artifacts
> Error using zeros
> Size inputs must be integers.
>
> Error in convert_event>artifact2artvec (line 179)
> artvec = zeros(length(artifact), endsample);
>
> Error in convert_event (line 103)
>      obj = artifact2artvec(obj,endsample);
>
> Error in ft_databrowser (line 501)
> artdata.trial{1}       = convert_event(artifact, 'boolvec', 'endsample',
> datendsample); % every artifact is a "channel"
>
>
> We did try to plot the raw *.cnt file (the cnt is recorded using curry
> 7) using ft_databrowser. It worked, but not the epoched data. This is
> the parameters we used for the cfg to run ft_definetrial and
> ft_preprocessing
>
>      cfg = [];
>      cfg.dataformat = 'ns_cnt';
>      cfg.headerformat= 'ns_cnt';
>      cfg.eventformat= 'ns_cnt';
>      cfg.trialdef.eventtype = 'stimtype';
>      cfg.trialdef.prestim = 0.5;
>      cfg.trialdef.poststim = 1.5;
>      cfg.trialdef.eventvalue = 114;
>      cfg.dataset = [dir filesep 'cnt' filesep subjectdata.subjectnr '_'
> subjectdata.initial '_' subjectdata.date '.cnt'];
>      cfg = ft_definetrial(cfg);
>      data = ft_preprocessing(cfg);
>
> The analysis is run on fieldtrip-20150522 and Matlab 2014a. Any help
> with this will be appreciated!
>
> Many thanks in advance,
> Carmen
>
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