Hi Alfonso,

I have a question regarding the aCompCor implemantation in CONN:

In the Bhezadi et al.(2007) paper the authors describe that they removed the linear trend from the time series prior to performing pca within the respective ROI, wm or csf:  ("Voxel time series from the noise ROI (either anatomical or tSTD) were placed in a matrix M of size N×m, with time along the row dimension and voxels along the column dimension. The constant and linear trends of the columns in the matrix M were removed prior to column-wise variance normalization. The covariance matrix C=MMT was constructed and decomposed into its principal components using a singular value decomposition.")

Is this step implemented in CONN? Also, is it necessary?


Thank you in advance!

Best,

Immanuel