We’ve all been there before. You’re sitting in the office, you’re out in an incredibly public place, you’re kneeling on the pew at church Sunday morning, and you just can’t help but start humming a couple bars of that song in your head. Sometimes you belt it out, sometimes you try to contain it. It’s almost always inappropriate for the situation you’re stuck in, but for some strange reason you just can’t get that song out of your head. Sometimes it follows you for hours. Sometimes it’s stuck with you for days. It just keeps popping back into your mind without warning, and you can’t help but start humming or singing or whistling along. The term for this is involuntary musical imagery (INMI), and it turns out there’s actually a medical reason for this. Thanks to MRI technology researchers are coming closer to explaining what the cause is.

Using this technology, they have determined that the frequency of INMI seems to be linked to the thickness of certain brain regions involved in musical imagery, which is essentially the ability to imagine absent sounds. The correlation between INMI frequency and cerebral cortex thickness appears to be associated with teo specific brain regions: the right Heschl’s gyrus (HG) and the right inferior frontal gyrus (IFG).

The HG is typically linked with auditory perception, how our brain interprets the sounds we hear, and voluntary musical imagery, while the IFG is believed to be involved in our memory of pitch. Researchers found that people who displayed reduced thickness in the right HG tended to experience INMI more frequently, something that contradicts earlier studies in which musical experts tended to have thicker cortices than non-experts.

Although this particular discovery left researchers with some puzzles to figure out, they did manage to find that individuals with frequent INMI found it to be incredibly useful in helping them get on with daily activities, as well as with memory formation.

It’s some pretty interesting stuff, and there’s still a lot to learn, but it’s clear that MRI technology will be a key tool in helping uncovering the mystery behind INMI.