Mirror neurons:

mirror neurons are neurons that are activated both when an animal performs an action and when it observes another performing the same action. The function of these neurons is not fully understood, and hypotheses have ranged from the suggestion mirror neurons help us to learn new movements through imitating others to speculation mirror neurons are important for helping us to understand the actions of others and display emotions like empathy. Many of these claims, however, are controversial, as scientists argue there is insufficient evidence to support them; see this article for more on that controversy.

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Know your brain: Mirror neurons