Scientists have uncovered clues about how the brain learns from watching the actions of others.
The brain activity of ballet dancers was monitored
The University College London team told the journal Cerebral Cortex the work may help the rehabilitation of stroke patients whose movement is impaired.
The brain activity of dancers and non-dancers was measured using an MRI scanner as they watched dancing videos.
They found the brain reacts differently when watching a move the individual was already skilled at performing.
They said the study also suggests that athletes and dancers could continue to mentally train while they are physically injured.
In the study, dancers from the Royal Ballet and experts in capoeira - a Brazilian martial arts form - were asked to watch videos of ballet and capoeira movements being performed while their brain activity was measured in a MRI scanner.
The same videos were also shown to other volunteers without specialist knowledge while their brains were scanned.
The researchers found greater activity in areas of the brain collectively known as the "mirror system" when the experts viewed movements that they had been trained to perform compared to movements they had not.
Volunteers skilled in neither discipline showed the same pattern of brain activity whether they watched ballet or capoeira.
Previous studies have found that the mirror system contains brain cells which fire up both when we perform an action and when we observe it.
However, the new study suggests this system is fine-tuned to each person's own particular range of skills.
Researcher Professor Patrick Haggard said: "A professional ballet dancer's brain will understand a ballet move in a way that a capoeira expert's brain will not.
"Our findings suggest that once the brain has learned a skill, it may simulate the skill without even moving, through simple observation.
"An injured dancer might be able to maintain their skill despite being temporarily unable to move, simply by watching others dance.
"This concept could be used both during sports training and in maintaining and restoring movement ability in people who are injured."
Fellow researcher Dr Daniel Glaser said: "Our study is as much a case of 'monkey do, monkey see' as the other way round.
"People's brains appear to respond differently when they are watching a movement, such as a sport, if they can do the moves themselves.
"When we watch a sport, our brain performs an internal simulation of the actions, as if it were sending the same movement instructions to our own body.
"But for those sports commentators who are ex-athletes, the mirror system is likely to be even more active because their brains may re-enact the moves they once made.
"This might explain why they get so excited while watching the game."
Deborah Bull, Creative Director at Royal Opera House, said: "As a former dancer, I have long been intrigued by the different ways in which people respond to dance.
"Through this and future research, I hope we'll begin to understand more about the unique ways in which the human body can communicate without words."