[FieldTrip] ft_definetrial() and ft_preprocessing()
Roberto Petrosino
robpetrosino at gmail.com
Sat Mar 10 22:28:56 CET 2018
Hi all,
I am trying to preprocess my eeg raw data (from BrainVision amplifiers), but I am having troubles with error I can’t figure out how to fix. Here’s the code:
> clear;
> clc;
>
> data_path = ‘/.../raw/';
>
> %STEP 1: reading the data in
> cfg = [];
> cfg.dataset = [data_path ’subj1.vhdr'];
>
> %high-pass filter
> cfg.preproc.hpfilter = 'yes';
> cfg.preproc.hpfiltord = 2; %known bug for filtering; can be avoided by changing the order of the filter (2 is random)
> cfg.preproc.hpfreq = 0.1; %in Hz
>
> %rereference
> cfg.preproc.reref = 'yes';
> cfg.preproc.channel = 'all';
> cfg.preproc.implicitref = ''; %on-line reference is empty
> cfg.preproc.refchannel = {'M1', 'M2'}; %the channels we want to rereference our data against. In this
> %case, we will rereference against the linked mastoids
>
> %updating channel locations; %% MPI/DCCN versions of actiCAP?
> cfg.layout = '/Users/.../MATLAB/fieldtrip-master/template/layout/acticap-64ch-standard2.mat'; %the file we want to extract electrode coordinates from
>
> %demean
> cfg.deman = 'yes';
> cfg.basewindow = [-.2 0];
>
> %STEP 2: defining trials and epoching
> cfg.trialdef.prestim = 0.2;
> cfg.trialdef.poststim = 1; % epochs will be -200 1000 ms
> cfg.trialdef.eventtype = 'Stimulus';
> cfg.trialfun = 'trialfun_congruency’; %customized function for the data
> data_in = ft_definetrial(cfg); %this will create a trl structure field, which is a list
> % of 3 columns, where every row describes a separate trial start, end and offset
> data_prej = ft_preprocessing(cfg);
This is the error that pops up:
> Error using ft_preprocessing (line 387)
> you must call FT_DEFINETRIAL prior to FT_PREPROCESSING
which is weird, since ft_definetrial() is called right before ft_preprocessing(). Does anyone know what the problem could be?
Thanks,
-Roberto
——
Roberto Petrosino
PhD student in Linguistics
CT Institute from Brain and Cognitive Sciences
University of Connecticut
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