Freestyle rapping — in which a performer improvises a song by stringing together unrehearsed lyrics — is a highly prized skill in hip hop. But instead of watching a performance in a club, Siyuan Liu and Allen Braun, neuroscientists at the US National Institute on Deafness and Other Communication Disorders in Bethesda, Maryland, and their colleagues had 12 rappers freestyle in a functional magnetic resonance imaging (fMRI) machine.
The artists also recited a set of memorized lyrics chosen by the researchers. By comparing the brain scans from rappers taken during freestyling to those taken during the rote recitation, they were able to see which areas of the brain are used during improvisation.
The rappers showed lower activity in part of their frontal lobes called the dorsolateral prefrontal cortex during improvisation, and increased activity in another area, called the medial prefrontal cortex. The areas that were found to be ‘deactivated’ are associated with regulating other brain functions. The results echo an earlier study of jazz musicians.
The findings also suggest an explanation for why new music might seem to the artist to be created of its own accord. With less involvement by the lateral prefrontal regions of the brain, the performance could seem to its creator to have “occurred outside of conscious awareness”, the authors write in the paper."