Fig. 4. Projections of the embeddings from the validated DL models.

a The projections of the embeddings inferred for the combined age and gender task were compared across a range of training sample sizes. Representational patterns of the brain are indeed learnt. In fact, they distill continually with increasing training sample size, and eventually evolve into separate gender clusters (i.e., red/F/female and blue/M/male clusters), both presenting a gradual spectrum of age (i.e., traceable light colored to dark colored). b The gender classification task (F females, M males) also revealed distinct clusters with very few outliers. c, d The projections for the age and MMSE regression tasks also revealed comprehensive trends in the spectrum, thus confirming that the implemented DL methods were indeed able to learn the task-specific brain representations.