I am working with my source space MEG timeseries as matlab variables. I loaded the data using "ResultsMat = in_bst_results(ResultsFile, 1);" so that I get all vertices and time points for this epoch. The source space was constructed using 15002 vertices - because we used unconstrained sources, we have 45006 data points for each time point. In total the epoch matrix (under ResultsMat.ImageGridAmp) is 45006 (15002 vertices * 3 orientations) x 4000 (timepoints).

How are the 3 orientations arranged along the 1st dimension of this matrix. Is it such that the first 3 data points are the three orientations for the first vertex? Or at the first 15002 data points the first orientation among all vertices?