Dear Peter,
I am wondering how to apply spectral DCM for the model structure example below. If there is any batch script suggestion for this example. Greatly appreciate your response for this and in the past below.
Best regards,
Ganesh
............................................
Dear Ganesh,
DCM.d should be of dimension [n x n x n] where n is the number of regions. The matrix DCM.d(:,:,1) represents non-linear connections from region 1, matrix DCM.d(:,:,2) represents non-linear connections from region 2, etc.
So to match the description you provided, model 2 should be:
DCM.d(1,3,2) = 1;
DCM.d(3,1,2) = 1;
Best,
Peter
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Ganesh Chand
Sent: 02 March 2016 13:52
To: [log in to unmask]
Subject: [SPM] Batch script for non-linear modulations in DCM
Dear SPM team,
I am having confusion how to write batch script for non-linear modulations in DCM.
DCM.options.nonlinear = 1;
Suppose I have THREE ROIs and they are intrinsically connected so I define
DCM.a = [1 1 1; 1 1 1; 1 1 1];
No bilinear modulation: DCM.b = zeros(3,3,0);
No external input to a node: DCM.c = zeros(3,3,0);
%model 1:
DCM.d = zeros(3,3,1);DCM.d(3,2,1) = 1; DCM.d(2,3,1) = 1; % First ROI has nonlinear modulation in the connections between second ROI and third ROI
save DCMM1 DCM
%model 2:
DCM.d = zeros(3,3,1);DCM.d(3,1,1) = 1; DCM.d(1,3,1) = 1; % Second ROI has nonlinear modulations in the connections between first ROI and third ROI
save DCMM2 DCM
%model 3:
DCM.d = zeros(3,3,1);DCM.d(2,1,1) = 1; DCM.d(1,2,1) = 1; %Third ROI has nonlinear modulation in the connections between first ROI and second ROI
save DCMM3 DCM
Are the models defined here the correct way for nonlinear modulations in DCM? If this is the correct way, my confusion is how the model 1 (for example) knows the first ROI is providing modulation effect?
Your advice is greatly appreciated in advance.
Best regards,
Ganesh Chand
|