Functional Magnetic Resonance Imaging (fMRI) was used to study the activation of cerebral motor networks during auditory perception of music in professional keyboard musicians (n=12). The activation paradigm implied that subjects listened to two-part polyphonic music, while either critically appraising the performance or imagining they were performing themselves. Two-part polyphonic audition and bimanual motor imagery circumvented a hemisphere bias associated with the convention of playing the melody with the right hand. Both tasks activated ventral premotor and auditory cortices, bilaterally, and the right anterior parietal cortex, when contrasted to 12 musically unskilled controls. Although left ventral premotor activation was increased during imagery (compared to judgment), bilateral dorsal premotor and right posterior-superior parietal activations were quite unique to motor imagery. The latter suggests that musicians not only recruited their manual motor repertoire but also performed a spatial transformation from the vertically perceived pitch axis (high and low sound) to the horizontal axis of the keyboard. Imagery-specific activations in controls were seen in left dorsal parietal-premotor and supplementary motor cortices. Although these activations were less strong compared to musicians, this overlapping distribution indicated the recruitment of a general 'mirror-neuron' circuitry. These two levels of sensori-motor transformations point towards common principles by which the brain organizes audition-driven music performance and visually guided task performance.
Using fMRI, cerebral activations were studied in 24 classically-trained keyboard performers and 12 musically unskilled control subjects. Two groups of musicians were recruited: improvising (n=12) and score-dependent (non-improvising) musicians (n=12). While listening to both familiar and unfamiliar music, subjects either (covertly) appraised the presented music performance or imagined they were playing the music themselves. We hypothesized that improvising musicians would exhibit enhanced efficiency of audiomotor transformation reflected by stronger ventral premotor activation. Statistical Parametric Mapping revealed that, while virtually 'playing along' with the music, improvising musicians exhibited activation of a right-hemisphere distribution of cerebral areas including posterior-superior parietal and dorsal premotor cortex. Involvement of these right-hemisphere dorsal stream areas suggests that improvising musicians recruited an amodal spatial processing system subserving pitch-to-space transformations to facilitate their virtual motor performance. Score-dependent musicians recruited a primarily left-hemisphere pattern of motor areas together with the posterior part of the right superior temporal sulcus, suggesting a relationship between aural discrimination and symbolic representation. Activations in bilateral auditory cortex were significantly larger for improvising musicians than for score-dependent musicians, suggesting enhanced top-down effects on aural perception. Our results suggest that learning to play a music instrument primarily from notation predisposes musicians toward aural identification and discrimination, while learning by improvisation involves audio-spatial-motor transformations, not only during performance, but also perception.
The realization of one’s musical ideas at the keyboard is dependent on the ability to transform sound into movement, a process called audiomotor transformation. Using fMRI, we investigated cerebral activations while classically-trained improvising and non-improvising musicians imagined playing along with recordings of familiar and unfamiliar music excerpts. We hypothesized that audiomotor transformation would be associated with the recruitment of dedicated cerebral networks, facilitating aurally-cued performance. Results indicate that while all classically-trained musicians engage a left-hemisphere network involved in motor skill and action recognition, only improvising musicians additionally recruit a right dorsal frontoparietal network dedicated to spatially-driven motor control. Mobilization of this network, which plays a crucial role in the real-time transformation of imagined or perceived music into goal-directed action, may be held responsible not only for the stronger activation of auditory cortex we observed in improvising musicians in response to the aural perception of music, but also for the superior ability to play ‘by ear’ which they demonstrated in a follow-up study. The results of this study suggest that the practice of improvisation promotes the implicit acquisition of hierarchical music syntax which is then recruited in top-down manner via the dorsal stream during music performance. In a study of audiomotor transformation in Parkinson patients, we demonstrated a dissociation between dysprosody in speech and music. While patients’ speech could reliably be distinguished from that of healthy individuals, purely on the basis of aural perception, no difference was observed between patients and healthy controls in their ability to sing improvised melodies.
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