FIGURE 2.

Summary of pertinent mapping physiologies. A, task-based mapping relies largely on modulation of brain oscillations > 40 Hz. These are known as gamma rhythms. These higher frequencies are typically associated with smaller cortical ensembles and show an increase in amplitude when active. Lower frequencies are thought to represent thalamocortical interactions. These rhythms typically have a broader cortical topography and decrease in amplitude when the cortex becomes active. B, resting-state mapping relies on the interaction of different cortical sites to define networks. These networks are identified by having a similar time series in infraslow rhythms, known as slow cortical potentials. If they have similar time series as indicated by the red and blue lines, they are connected; if they are not correlated or are anti-correlated (dotted line), then these sites are not functionally connected.