People's memories can often be triggered by music and a study of 13 students by researchers at the University of California, Davis looked to see what happens in people's brains when this was going on. The students were played excerpts of 30 different tunes, chosen to have been in the charts when they were growing up, at the same time as they had magnetic resonance imaging (MRI) scans. After each excerpt the student responded to questions about the tune including whether it was familiar or not, how enjoyable it was and whether it was associated with any particular incident, episode or memory. How many memories a tune triggered corresponded to the amount of activity in the upper part of the medial pre-frontal cortex; part of the brain where memories of our past are supported and retrieved. This part of the brain is one of the last to be affected by Alzheimer's disease and it has often been observed that tunes can bring back memories in Alzheimer's sufferers when little else does.
You can find out more about this research at