[Marsbar-users] Probelms with compute_contrasts() ?

[<he...@um...>]

Dear MarsBaR experts,
    I'm trying to model an ROI using a batch script (adapted from the 
code provided in the marsbar FAQ).  It works without a hitch (using 
marsbar-devel in matlab 7.0.4), but I don't understand the output of 
compute_contrasts(), specifically MVres (please see below).

    I just need a way of visualizing both the actual and modeled time 
series (with or without compute_contrasts).  How do I do this?

    Thanks in advance,
    Jay

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spm_name = '/my/path/SPM.mat';

roi_file = '/my/path/my_roi.mat';
 
% Make marsbar design object
D  = mardo(spm_name);

% Make marsbar ROI object
R  = maroi(roi_file);

% Fetch data into marsbar data object
Y  = get_marsy(R, D, 'mean');

x = summary_data(Y); % get summary time course(s)
plot(x, 'r-');      %<<<< Looks fine.
......

marsS = compute_contrasts(E, 1:length(xCon));  %Works fine

plot(marsS.MVres(1).y_obs);  %Looks inverted, i.e., like (-n*x) - a,
	%where is x is the summary time course above, n and a are scalars.
	%This is supposed to be "observerd temporal response", so I don't
	%understand why this isn't identical to x above.

plot(marsS.MVres(1).y_pre);  %This supposed to be the predicted response, but it
	%doesn't look right.
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