Temporal Dynamics of Intraparietal Sulcus Activation in Response to Musical Uncertainty: An Fmri Study of the Diminished Seventh Chord

Abstract

Tonality and harmony in music provide a structured framework to explore the neural mechanisms underlying uncertainty. The diminished seventh (dim7) chord, characterized by its pronounced tonal ambiguity and multiple potential resolutions, serves as an ideal stimulus for examining tonal uncertainty. This fMRI study investigated neural activity elicited by the dim7 chord in listeners with refined music listening skills, focusing on three harmonic progressions: CHANGE, modulating to a distantly related tonality; RETURN, resolving to the original tonality; and PERSIST, sustaining tonal ambiguity through repeated dim7 chords. A finite impulse response model was used to analyze responses in regions associated with uncertainty processing. The bilateral intraparietal sulcus (IPS) uniquely exhibited distinct temporal activation patterns across the three conditions. In the CHANGE condition, IPS activity initially decreased, likely reflecting a downregulation of confidence in the outdated tonal model, followed by an increase as sensory evidence for a new tonal model accumulated. Meanwhile, the PERSIST condition elicited a progressive bilateral increase in IPS activity, likely reflecting heightened cognitive demands for maintaining and evaluating multiple tonalities. These findings underscore the nuanced role of the IPS in dynamically adjusting internal models based on sensory input.

Keywords: Intraparietal sulcus, Music cognition, Predictive coding, Model updating, Uncertainty, fMRI