Increased activation in the left ventrolateral prefrontal cortex and temporal pole during tonality change in music

In human music, the tonality (key) may change to punctuate sectional structures and to produce emotional effects. A tonality change would sound "smoother" when it is supported by appropriate harmony. This functional magnetic resonance imaging study examined the neural substrates of the processing of tonality change. We used a 2 × 2 factorial design with factors tonality change (tonality changed versus tonality unchanged) and harmonization (harmonized versus unharmonized). Participants were asked to covertly sing the pitch names in the movable-do system along with the heard melody. Repetitions of this melody were associated with or without a tonality change, with equal probability in a pseudo-random order. Our result demonstrated that tonality changes elicited increased activation in the left ventrolateral prefrontal cortex and left temporal pole. When a tonality change occurred, the left ventrolateral prefrontal cortex might underpin the cognitive control for retrieving the pitch-naming rule of the new tonality, whereas the left temporal pole might integrate the melodic/harmonic context and emotional meanings of music. This study provides a new insight into the cognitive and emotional processing of music.