Fig. 1

Illustration of intersubject alignment of brain images and unitary model of the limbic system. Blue and green rectangles represent the same functional area in two subjects, while yellow rectangles illustrate the overlap of the two individual areas after alignment. With structural alignment, there can be a complete misalignment of small functional areas (a) or partial misalignment of large functional areas (b) due to functional–anatomical variability or poor anatomical contrasts in MRI imaging. If an additional step of functional alignment is performed, an optimised overlap of functional areas is obtained. c The limbic system as originally depicted by Papez⁵² and (d) diagram of the unitary model of the limbic system^{49,50,51,165,166,167,168}