Cross-spatial scale processing of hierarchical auditory sequences in human brains revealed using 7 T magnetic resonance imaging.

Abstract

Human auditory cognition involves multiregional hierarchical processing, yet the neural mechanisms integrating cortical layers and large-scale networks remain unclear. Using high-resolution fMRI, we investigate cross-spatial scale dynamics during hierarchical auditory processing. Distinct activations across layers of superior temporal gyrus (STG) and inferior frontal gyrus (IFG) are detected during standard stimuli and violation. We identify the layer-specific effective connectivity among key nodes in the auditory hierarchy using dynamic causal modelling. The results are consistent with hierarchical predictive coding schemes: (i) tone and sequence processing provide input to the superficial and middle layers of STG, respectively. (ii) Forward connections came from the superficial layers of STG, while (iii) backward connections implicated the deep layers of IFG. The integration of mesoscale and macroscale activities confirms the interaction of superficial/middle layers of STG with higher-level regions. These findings elucidate a multiscale mechanism coordinating cortical layers and distributed networks in hierarchical auditory processing.