A DMN-based functional taxonomy of the resting human brain: is essential really invisible to the eye?

Once upon a time, the Little Prince came across a planet nhabited by an old geographer who wrote voluminous books. Nevrtheless, he was not able to answer to the Little Prince, who was ondering for the presence of oceans, mountains, towns or rivers n the planet. As a matter of fact, the geographer usually asked uestions to explorers without ever leaving his desk: he first noted own what they recalled from their travels with a pencil, and nly after they had provided cogent proofs, he put them down in nk. Making exciting and clinically relevant discoveries, and possibly utting them down in ink, is still a fundamental scientific requiite for worldwide ‘explorers’. In 2001, a group of neuroscientists eported that when an individual is alert but not actively engaged n cognitive tasks, a spontaneously organized neural activity occurs n a unique constellation of brain regions called the Default Mode etwork (DMN), which mainly involves the posterior cingulate ortex, the precuneus and regions of the ventromedial prefrontal ortex (Raichle et al., 2001). Since then, DMN structure and funcions have been investigated across the whole human lifespan, rom its emergence in 48-hour-old newborns (Gao et al., 2009) o its disappearance in dead brains (Boly et al., 2009). DMN-based esearch provided insights into the intrinsic functional architecture f human brain, as well as inter-individual differences in strucural connectivity and neural activations. In addition, abnormalities nd disruptions between healthy and pathological conditions were iscovered (Fig. 1). Notably, in the very last couple of months a new perspective has een emerging, since scattered interdisciplinary pieces of evidence re accounting for what we can define the ‘predictive potential’ of MN. As a matter of fact, peculiar patterns of DMN activity and onnectivity seem to anticipate future behavioral phenotypes and linical impairment. In other words, DMN structure and function ot only constitute the behavioral and neuropathophysiological orrelates of potential and in fieri neurological and psychiatric disases (Fox and Raichle, 2007; Sandrone, 2012), but they can also