What is it about a song that instantly jerks your mind back to when you heard it at a particular time?

I heard an old song when I was driving home after spending a very enjoyable evening with two friends. At the time, the song fit my mood perfectly and I sang along.

Today, when I heard the song again, it immediately reminded me of that night. How much time will pass before this song no longer reminds me of them? Or will the memory forever be connected to the song?

I think that this is a relatively common occurance. Whenever I hear 'Cross My Heart' by George Strait I tear up and think of my first dance with my husband. Any song by Queen will always remind me of high school basketball games.

But, I also do this with television shows. I was scrapbooking one night while watching tv. Now, whenever I look at that page in my album, I think about what was on tv that night.

What is it in our brains that makes these connections?

ang'I cross my heart and promise to/Give all I've got to give to make all your dreams come true./In all the world you'll never find a love as true as mine. *sniff*'ela