Primary and nonprimary auditory cortex connectivity with brain regions involved in cognitive and emotional processing: in mouse and human.

Auditory cortex connectivity extends beyond the processing of acoustic stimuli, playing a crucial role in cognitive and emotional regulation through its interactions with higher-order brain regions. Although the neural mechanisms underlying acoustic information processing along the auditory pathway are well-documented, the connections supporting auditory-related cognitive and emotional processing, particularly in comparative studies between mice and human adults, are not yet fully clarified. In this study, we aim to investigate connections between the auditory cortex and brain regions involved in cognitive and emotional processing using retrograde fluoro-gold (FG) tracer in mice and 3-tesla high-resolution diffusion tensor tractography (DTI) in human adults. The FG injections into the primary and nonprimary auditory cortices showed afferent connections with cortical (olfactory bulb, piriform, orbitofrontal, cingulate, motor, primary somatosensory, insular, visual, parietal, entorhinal and perirhinal cortices), subcortical (amygdala, hippocampus, globus pallidus, claustrum, bed nucleus of stria terminalis, diagonal band of the Broca and medial septal nucleus) and brainstem (raphe nuclei, pedunculopontine nucleus and locus coeruleus) structures. The DTI data obtained from human adults mostly corresponded with the experimental findings. Auditory cortical processing integrates auditory signals with other sensory, limbic and motor inputs. The connections collectively may suggest its role in cognitive and emotional functions. The auditory cortex is likely a critical hub within the neural circuitry underlying multisensory integration, decision-making, prediction, learning and memory functions. Understanding the connectivity of the auditory cortex can deepen our insight into its contribution to cognitive/emotional functions, offering new perspectives on the underlying mechanism linking hearing deficits with cognitive/emotional disorders.