FIGURE 1.

Functional neuroimaging: evolution of reference frame. (A) In its early years, the sole focus of functional neuroimaging techniques (e.g., fMRI) was to localize brain function to distinct brain regions. (B) The first paradigm shift took place with experimental validation of functional integration over distinct brain areas using measures of functional connectivity and shifting of the reference frame to the whole of the brain. Adapted from “Decreased functional brain connectivity in adolescents with internet addiction,” by Hong et al. (2013). Copyright 2013 by Hong et al. used under Creative Commons Attribution License. (C) The emerging techniques to assess between-brain functional connectivity calls for a second paradigm shift from a single brain to a multi-brain reference frame. Adapted from “Toward a two-body neuroscience,” by Dumas (2011). Copyright 2011 by Landes Bioscience. Adapted with permission.