It is not individual neurons that reflect, but aims: neuronal networks (midpoints), that are activated by what happens to the other. This awakens similar aims that have the same topic, which among other things, generate feelings like those that the other has.
In this way, you can empathize with other people's feelings.
Mirror neurons were discovered more accidentally by Giacomo Rizzolatti in 1996.
He was concerned with the reaction of individual neuron cells and not with neuron networks. This gave rise to the term “mirror neurons.” Actually, it should read: network reflections (or center reflections).