Fig. 1

a Representation of the U-net with an encoder depth of three. b Feature maps of the second convolutional layer and the second last convolutional layer are depicted. One feature per layer is marked in red and shown below in c. Coronal, sagittal, and transversal slices of the corresponding features maps are shown. The second convolutional layer shows a WM-like feature, which, however, is not homogeneous in all three dimensions. The last convolution layer depicts a homogeneous WM-like feature in all three dimensions. No colorbars were shown because all features are in arbitrary units