.sqd to FieldTrip steps

Akiko Ikkai akiko at NYU.EDU
Fri May 8 20:17:06 CEST 2009


I just started learning to do MEG experiments, and am very new to FieldTrip.

I have a simple continuous recording (120s, 1000Hz) of MEG to test noise level, therefore no event type. My goal with this data is to look at frequency power distribution to check for any irregular spikes. We collect data in .sqd format. It appears that sqd format is not supported, so I simply renamed the data to .raw, which I could read into matLab using "read_fcdc_header" and "read_fcdc_data" (returns 192 x120000 matrix). However, since my data has no events, I'm not sure what inputs need to be fed into "definetrial".

When I tried
cfg = [];
cfg.dataset = 'Out.raw';
cfg = definetrial(cfg);

I got this message
??? Error using ==> definetrial at 151
no trialfunction specified, see DEFINETRIAL for help

If you could give me some advise about how I should proceed (e.g. what parameters I need to have, and how I could create/retrieve them), it'll be very helpful. Also, if there are any specific notes about "using sqd and FieldTrip", please let me know as well.

Thanks in advance! Akiko Ikkai

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