"If rapping off the top of the dome was a requirement to be a rapper then the majority of the rappers in the game right now would not be where they are," says Toronto rapper DijahSB. "It's very difficult."

Freestyling isn't a prerequisite to be a fantastic rapper these days. But it still gets respect, given its history in Black communities and the technique and creative skill required to do it well. "Freestyling is like spontaneity in poetic form," says fellow-Torontonian Phoenix Pagliacci.

In this video, Angelyn Francis takes us through the history of the form and what some brain research using fMRI scans tells us about what's happening inside the minds of freestylers.

Watch the video:

"Freestylers pretty much shut down the parts of their brain that interfere with creativity, flow and improv," says filmmaker Angelyn Francis. 4:03

Francis explains: "Freestyling off the dome has more to it than just how quickly your mind can move — it's more about which parts of your mind you're letting move. There's actually something pretty cool happening in your brain when you're riffing on the spot." In a study done by scientists at The National Institute on Deafness and Other Communication Disorders (NIDCD), researchers took fMRI scans of 12 rappers while they rapped both memorized and freestyle bars. The fMRIs, which measure blood flow to the brain to determine which parts are active or resting, found a significant difference in brain activity between those freestyling and those rapping a rehearsed verse, as seen in the graphic above.

See the orange parts of the brain? "These are the areas that are connected to organization, motivation and integration," Francis says. While freestyling, these sections are lit up. "Meanwhile, the portions responsible for self monitoring and control are turned down. So the parts of the brain that second guess, focus on perfection and overthink are less active than the other parts."

While machines can't tell us what makes freestyling so incredible to watch or explain the creativity behind it, thinking about the incredible bursts of brain activity going on behind the scenes as a rapper freestyles makes the art all the more impressive than it already was.