Checks each MEG channel to see if it goes over threshold during any of the trials
Input:
bexp is a TxSxC matrix, where T are the trials, S is time, and C are the MEG channels
bexp_ext is a TxSxC matrix, where T are the trials, S is time, and C are the external trigger channels
threshold is the threshold in tesla (T) (default is 3000*1e-15 T = 3000 fT)
Output:
rejectedTrials is a vector containing the trial numbers of trials in
which an MEG channel exceeded threshold (the channel that exceeded
threshold is displayed to the screen while the program is running).
Example:
rejectedTrials = meg_rejection(bexp,bexp_ext,3000*1e-15);
returns a list of rejected trials for threshold at 3000 fT.
[note]
sample script
[history]
****-**-** (WHOM) initial version
2010-01-27 (Sako) registered with CVS
Copyright (C) 2011, ATR All Rights Reserved.
License : New BSD License(see VBMEG_LICENSE.txt)0001 function rejectedTrials = vb_test_meg_rejection(bexp,bexp_ext,threshold) 0002 % Checks each MEG channel to see if it goes over threshold during any of the trials 0003 % Input: 0004 % bexp is a TxSxC matrix, where T are the trials, S is time, and C are the MEG channels 0005 % bexp_ext is a TxSxC matrix, where T are the trials, S is time, and C are the external trigger channels 0006 % threshold is the threshold in tesla (T) (default is 3000*1e-15 T = 3000 fT) 0007 % Output: 0008 % rejectedTrials is a vector containing the trial numbers of trials in 0009 % which an MEG channel exceeded threshold (the channel that exceeded 0010 % threshold is displayed to the screen while the program is running). 0011 % 0012 % Example: 0013 % rejectedTrials = meg_rejection(bexp,bexp_ext,3000*1e-15); 0014 % returns a list of rejected trials for threshold at 3000 fT. 0015 % 0016 % [note] 0017 % sample script 0018 % [history] 0019 % ****-**-** (WHOM) initial version 0020 % 2010-01-27 (Sako) registered with CVS 0021 % 0022 % Copyright (C) 2011, ATR All Rights Reserved. 0023 % License : New BSD License(see VBMEG_LICENSE.txt) 0024 0025 if nargin<3 0026 threshold = 3000*1e-15; % default threshold is 3000 fT 0027 end 0028 0029 endTriggerCh = 31; % end of trial is marked by trigger on channel 249, which is channel 31 in bexp_ext 0030 waitForResponseCh = 30; % waiting for response trigger on channel 248 0031 LbuttonCh = 22; % subject left button presses on channel 240 0032 RbuttonCh = 23; % subject right button presses on channel 241 0033 0034 triggerThresh = 1; % threshold for testing whether external trigger is on or off 0035 0036 rejectedTrials = []; 0037 0038 for trial = 1:size(bexp,3) % cycle through each trial 0039 0040 trialEndTime = find(bexp_ext(endTriggerCh,:,trial)>triggerThresh,1,'first'); % find the time of the end of the trial 0041 0042 if isempty(trialEndTime) % make sure the end of the trial was found 0043 0044 waitForResponseTime = find(bexp_ext(waitForResponseCh,:,trial)>triggerThresh,1,'first'); % find when subject is cued to respond 0045 0046 if isempty(waitForResponseTime) 0047 disp(['Warning: Could not find the end of trial trigger for trial ', num2str(trial), '!']); 0048 trialEndTime=size(bexp,2); % could not find the end of trial trigger, so set the trial end time to the maximal possible value 0049 else 0050 % find the first button press after the waitForResponse trigger 0051 buttonPress = find(min(bexp_ext([LbuttonCh, RbuttonCh],waitForResponseTime:size(bexp,2),trial))<triggerThresh,1,'first'); 0052 if isempty(buttonPress) 0053 buttonPress=1; 0054 end 0055 trialEndTime= waitForResponseTime+buttonPress-1; 0056 end 0057 end 0058 0059 for channel = 1:size(bexp,1) % cycle through each meg channel 0060 overbounds = find(abs(bexp(channel,1:trialEndTime,trial))>threshold,1,'first'); % find the first occurence of the absolute value of the channel exceeding threshold 0061 if ~isempty(overbounds) 0062 disp(['Channel ', num2str(channel), ' during Trial ', num2str(trial), ' is noisy']); 0063 rejectedTrials=union(rejectedTrials,trial); % channel went out of bounds, so reject this trial. 0064 end 0065 end 0066 end