The only training required in our method is to con-
  struct linear models that map fMRI signals to each LDM
  component, and no training or fine-tuning of deep-learning
  models is needed.
  
  ...
  
  To construct models from fMRI to the components of
  LDM, we used L2-regularized linear regression, and all
  models were built on a per subject basis. Weights were
  estimated from training data, and regularization parame-
  ters were explored during the training using 5-fold cross-
  validation.