Let's get geeky on music. Ever wonder what's happening in a musician's brain when they're actually playing a song?

What about when a musician starts improvising - starts playing music directly "off the cuff"?

Thanks to the research from Dr. Charles Limb - an ear and throat doctor and surgeon who also happens to be obsessed with music - we now have a much better idea.

Over the last few years - Limb put jazz musicians and rappers into MRI machines to see what's happening in their brain when they improvise or freestyle rap.

Inside of the MRI machine - he'd have them simply play scales followed by having them improvise on scales - and then he'd have the musicians play a memorized piece of music - and then finally he'd have them play an improvised version of that.

What he found was when one of the subjects started improvising - parts of the brain that are associated with "self-expression" were activated - language regions and at times regions associated with visual imagery activated too.

But what's really interesting is that regions of the brain that are involved in inhibition - the parts of the brain that self-monitor and hold us back from saying and doing offensive or inappropriate things - were actually LESS active during improvisation.

Limb points out, "Without this type of creativity, humans wouldn't have advanced as a species."

He's right, understanding creativity and how humans improvise - especially in groups - isn't just fascinating: it's critical to understanding how humans have been so successful as a species.