Left: histogram of the 24th of the 64 latent space dimensions for the auto-encoder training and test samples as derived from the initial prior shown in the left of Fig. 2. The 24th latent dimension of the observation is materialized by the dashed vertical line. Right: same histogram but derived from spectra simulated from the prior proposal generated after the single round of MRI (shown in the right of Fig. 2). The shape of the histogram evolves towards a Gaussian-like shape and is better centered around the observation.