Amygdala and insula contributions to dorsal-ventral pathway integration in the prosodic neural network

Abstract: Speech prosody enables communication of emotional intentions via modulation of vocal intonations. Reciprocal interactions between superior temporal (STG) and inferior frontal gyri (IFG) have been shown to anchor a neural network for prosodic comprehension, which we refer to as the Prosody Neural Network (PNN). Although the amygdala is critical for socio-emotional processing, its integral functional and structural role in processing social information from speech prosody as well as its role in the PNN is largely unexplored including inconsistent recent empirical findings. Here, we used magnetoencephalography and diffusion magnetic resonance imaging of white-matter pathways to establish that the PNN is characterized by (1) a robust amygdala-cortical functional connectivity that dynamically evolves as prosodic interpretation progresses, (2) direct structural fiber connections between amygdala and STG/IFG traversing a ventral white-matter pathway, and (3) robust amygdala-insula functional connectivity and structural insula fiber projections to arcuate STG-IFG connections. These findings support a role for functional and structural amygdala-centric ventral pathways in combining speech features to form prosodic percepts. They also highlight insula contributions to prosodic comprehension, potentially via vertical integration of amygdala-centric ventral processing into dorsal pathways responsible for prosodic motor articulation and speech planning.