[FieldTrip] How to import *.cnt datafile from NeuroScan?

蔡林 bertram0611 at pku.edu.cn
Sun Jul 8 09:50:20 CEST 2012

Dear FieldTrip list members,

I wanna analyse the *.cnt datafile from NeuroScan. But I don't know how to do that. Because there are not detailed scripts. In my exp, the trigger code is 14. I don't what is eventvalue that equals trigger code? My EEG was recorded from 62 Ag/AgCl electrodes mounted in an elastic cap (Quick-Cap, NeuroScan Inc.,Herndon, Virginia, USA). Recordings were referenced to the left mastoid, but rereferenced to linked mastoids offline. The horizontal and vertical electrooculogram was also monitored. Electrode impedances were kept below 5 kO. The EEG and electrooculogram were amplified with a band-pass from DC to 70Hz and the sample rate was 500 Hz.The epoch interval was 1200ms, ranging from 200ms before the onset of the critical word to 1000 ms after it.I used a 100-ms poststimulus baseline for the critical words.
can you give an example that analysing *.cnt data.
my script and problems as follows:
   cfg = []
   cfg.datafile   = 's01.cnt'
   cfg.headerfile = 's01.cnt'
   cfg.channel = 'all'
   cfg.eventvalue = '14'
   raw = ft_definetrial(cfg);
Warning: no trialfun was specified, using trialfun_general 
> In ft_definetrial at 123
evaluating trialfunction 'trialfun_general'
??? Reference to non-existent field 'trialdef'.

Error in ==> trialfun_general at 29
if isfield(cfg.trialdef, 'eventvalue')  && isempty(cfg.trialdef.eventvalue   ),
cfg.trialdef = rmfield(cfg.trialdef, 'eventvalue' ); end

Error in ==> ft_definetrial at 175
    [trl, event] = feval(cfg.trialfun, cfg);
best regards

Lin Cai
Department of Psychology, Peking University, Beijing 100871, P.R.China

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