Neural substrates of spontaneous musical performance: an FMRI study of jazz improvisation

Abstract

To investigate the neural substrates that underlie spontaneous musical performance, we examined improvisation in professional jazz pianists using functional MRI. By employing two paradigms that differed widely in musical complexity, we found that improvisation (compared to production of over-learned musical sequences) was consistently characterized by a dissociated pattern of activity in the prefrontal cortex: extensive deactivation of dorsolateral prefrontal and lateral orbital regions with focal activation of the medial prefrontal (frontal polar) cortex. Such a pattern may reflect a combination of psychological processes required for spontaneous improvisation, in which internally motivated, stimulus-independent behaviors unfold in the absence of central processes that typically mediate self-monitoring and conscious volitional control of ongoing performance. Changes in prefrontal activity during improvisation were accompanied by widespread activation of neocortical sensorimotor areas (that mediate the organization and execution of musical performance) as well as deactivation of limbic structures (that regulate motivation and emotional tone). This distributed neural pattern may provide a cognitive context that enables the emergence of spontaneous creative activity.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Low complexity (Scale) and high complexity (Jazz) experimental paradigms used to study spontaneous musical creativity.

In the upper portion of the figure, the non-ferromagnetic MIDI piano keyboard that was used during functional MRI scanning is shown. This keyboard had thirty five full-size piano keys which triggered high-quality piano sound samples generated outside of the scanner, which were immediately routed back to the musicians using audiophile quality electrostatic earphone speakers. During scanning, subjects were randomly cued to play either the over-learned control condition or to improvise spontaneously. For Scale's control condition, subjects repeatedly played a one octave ascending and descending C major scale in quarter notes for the duration of the block (ScaleCtrl, upper left). For Scale's improvisation condition, subjects improvised in quarter notes only, selecting all notes from within one octave and from the C major scale notes alone (example shown under ScaleImprov, upper right). For Jazz's control condition, subjects played a novel melody that was memorized prior to scanning (JazzCtrl, lower left). For Jazz's improvisation condition, subjects improvised using the composition's underlying chord structure as the basis for spontaneous creative output (example shown under JazzImprov, lower right). Note that for JazzCtrl and JazzImprov, eighth notes are typically performed with a “swing” feel that is not accurately represented using standard musical notation, in both the control and improvisation conditions. Audio samples of the four musical excerpts shown here are provided in Supporting Information.

Figure 2. Axial slice renderings of mean activations (red/yellow scale bar) and deactivations (blue/green scale bar) associated with improvisation during Scale and Jazz paradigms.

In both paradigms, spontaneous improvisation was associated with widespread deactivation in prefrontal cortex throughout DLPFC and LOFC, combined with focal activation in MPFC. In addition, increases in sensorimotor activity and decreases in limbic activity were seen in both paradigms. Activations were identified through inclusive masking of the contrast for [Improv–Control] with the contrast for [Improv–Rest], and deactivations were identified through inclusive masking of the contrast for [Control–Improv] with the contrast for [Rest–Improv] for both Scale and Jazz paradigms. The scale bar shows t-score values and the sagittal section shows an anatomical representation of slice location; both scale bar and sagittal slice insets apply equally to Scale and Jazz data. Labels refer to axial slice z-plane in Talairach space.

Figure 3. Three-dimensional surface projection of activations and deactivations associated with improvisation during the Jazz paradigm.

Medial prefrontal cortex activation, dorsolateral prefrontal cortex deactivation, and sensorimotor activation can be seen. The scale bar shows the range of t-scores; the axes demonstrate anatomic orientation. Abbreviations: a, anterior; p, posterior; d, dorsal; v, ventral; R, right; L, left.