This study from University College suggests that motor experts like professional dancers are able to activate more brain areas while watching familiar movements in others. The brain areas activated included areas for motor planning, sensory-motor imagery, and personal memory. This is a similar to a research report that found that professional pianists watching other pianists activated sensory motor areas (kinesthesia!) just by watching.
Imagery is a powerful guide to learning - it unites diverse brain areas and provides patterns for coordinated actions that may be used for other purposes in the future. One of the reasons that sensory processing disorders can have such a profound effect on behavior (children may develop anxiety, avoidance, isolation), is that these children have fewer opportunities to build coordinated sensory-motor patterns as they interact with their environment, so they may always appear to encountering things for the first time.
Better Imagery with Expert Dancers