Notes in a musical scale convey different levels of stability orincompleteness, forming what is known as a tonal hierarchy.Levels of stability conveyed by these scale degrees are partlyresponsible for generating expectations as a melody proceeds,for emotions deriving from fulfillment (or not) of those expectations,and for judgments of overall melodic well-formedness.These functions can be extracted even during imagined music.We investigated whether patterns of neural activity in fMRIcould be used to identify heard and imagined notes, and if patternsassociated with heard notes could identify notes that weremerely imagined. We presented trained musicians with thebeginning of a scale (key and timbre were varied). The nextnote in the scale was either heard or imagined. A probe tonetask assessed sensitivity to the tonal hierarchy, and state andtrait measures of imagery were included as predictors. Multivoxelclassification yielded above-chance results in primaryauditory cortex (Heschl’s gyrus) for heard scale-degree decoding.Imagined scale-degree decoding was successful in multiplecortical regions spanning bilateral superior temporal, inferiorparietal, precentral, and inferior frontal areas. The right superiortemporal gyrus yielded successful cross-decoding ofheard-to-imagined scale-degree, indicating a shared pathwaybetween tonal-hierarchy perception and imagery. Decoding inright and left superior temporal gyrus and right inferior frontalgyrus was more successful in people with more differentiatedtonal hierarchies and in left inferior frontal gyrus among peoplewith higher self-reported auditory imagery vividness, providinga link between behavioral traits and success of neural decoding.These results point to the neural specificity of imagined auditoryexperiences—even of such functional knowledge—butalso document informative individual differences in the precisionof that neural response.
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