Neural Responses to Musical Consonance and Dissonance in the Human Superior Temporal Gyrus

• ¹ University of California, Berkeley, United States
• ² California Pacific Medical Center, Neurology and Neurosurgery, United States
• ³ University of California, Berkeley, Helen Wills Neuroscience Institute, United States
• ⁴ University of California, Berkeley, Psychology, United States
• ⁵ Stanford University, Neurology and Neurological Sciences, United States

Research on the neural basis of consonance and dissonance processing in music has depended on non-invasive electrophysiological and functional imaging techniques in humans. However, the fine-grained spatiotemporal dynamics of consonance and dissonance perception within the auditory cortex remain unknown. Using electrocorticography (ECoG) that records electrophysiological signals directly from subdural grids located on the surface of human cortex, we aimed to investigate whether subregions of the superior temporal gyrus (STG) are differentially responsive to consonant and dissonant chords. We recorded from four patients with extensive ECoG coverage in either left or right STG as well as medial intra-Sylvian regions as they passively listened to highly consonant and highly dissonant piano chords. We assessed both the high-gamma (HG) ECoG bandwidth (70-150 Hz) and event-related potentials (ERPs), and we observed two cortical sites of interest: one that had equivalent HG responses to both consonant and dissonant chords, and another, 1-2 cm anterior to the former site, that showed increased HG responses to dissonant chords (p<0.05, FDR corrected) on single-trials at 50-200ms after stimulus onset. ERPs showed a similar spatial distribution pattern in the STG. These data support differential consonant and dissonant chord processing at a resolution of 1-2 cm in bilateral STG. We propose that the HG pattern for dissonant chord processing reflects heightened synchronous neuronal firing in response to the phenomena of beats or "roughness" that characterize our perception of dissonance. The distinction between anterior and posterior activations may reflect the hierarchical organization of the auditory cortex, where anterolateral regions are preferentially tuned to auditory stimuli of increasing complexity and pitch salience. In sum, the findings indicate that direct cortical recording can track perceptual aspects of musical processing with temporal and spatial precision.