function [ trials ] = trial_definition_ft( file_list, marker_name, prestim, postim, emg_names )
%trial_definition_ft Define trials
%   Detailed explanation goes here
trials = [] ;
for file_id = 1:length(file_list)

    cfg=[];
    cfg.dataset             = file_list{file_id};
    cfg.trialdef.eventtype  = marker_name ;
    cfg.trialfun            = 'mrkfiftrialsel'; 
    cfg.trialdef.poststim   = postim ;
    cfg.trialdef.eventvalue = 0 ;
    cfg.trialdef.prestim    = prestim ; 
    cfg.channel          = {'MEG'};

    cfg = ft_definetrial(cfg);
    
    trials_tmp=ft_preprocessing(cfg);
    
    if ~isempty(emg_names)
       %% Preprocess emg 
       tmp_meg_data = trials_tmp ; 
       trials_tmp = [] ;
       cfg              = [];
       cfg.dataset      = tmp_meg_data.cfg.dataset;
       cfg.trl          = tmp_meg_data.cfg.trl;
       cfg.continuous   = 'yes';
       cfg.demean       = 'yes';
       cfg.dftfilter    = 'yes';
       cfg.channel      = emg_names;
       cfg.hpfilter     = 'yes';
       cfg.hpfreq       = 10;
       cfg.rectify      = 'yes';
       emg = ft_preprocessing(cfg);
       trials_tmp = ft_appenddata([], tmp_meg_data, emg);
    end
    
    if file_id > 1
        trials = ft_appenddata([], trials, trials_tmp);
    else
        trials=trials_tmp;
        grad_tmp=trials.grad;
    end
    
end

if file_id > 1
    trials.grad = grad_tmp ;
end

end