In Brief: The Quirky Brain: Why songs get "stuck" in people's heads
Most people have experienced this phenomenon at one point or another: a mental replaying of a catchy tune, seemingly for no reason. The tunes that get stuck in people's heads are often advertising jingles, television theme songs, pop songs, and children's songs.
In scientific literature and in the lay press, the phenomenon goes by many names: sticky music, stuck songs, involuntary musical imagery, cognitive itch, mental concert, and ohrwurm (translated literally as "earworm").
Studies involving functional MRI have revealed that people "hear" internal melodies in much the same way as they hear music from a real orchestra. In both cases, the auditory cortex — the part of the brain that processes sounds — becomes active. When the music is playing only inside someone's head, however, only part of the auditory cortex is activated, and it is likely that other parts of the brain — such as those involved in memory — also contribute.