Anatomical and Functional Evidence for Vestibular-Auditory Integration via the LVN–IC Pathway

초록

The vestibular system plays a critical role in maintaining balance and spatial orientation. . It functions independently, but it works more effectively when it cooperates with other sensory systems. While sensory integration is important, relatively few studies have specifically addressed the interaction between the vestibular system and auditory processing. Evidence suggests a connection via the lateral vestibular nucleus (LVN); a study found LVN projections to the dorsal cochlear nucleus co-labeled with VGLUT2, implying a potential anatomical link. However, the precise neural pathways in vestibular auditory interaction are still not well understood. This study investigated the interaction between the inferior colliculus (IC), a hub that integrates auditory inputs, and the LVN, and evaluated whether the LVN plays a key role in integration of auditory-vestibular system. Retrograde virus injection into the IC resulted in labeled neurons in the LVN, and anterograde virus injection into the LVN revealed labeled fibers in the ventromedial region of the IC. In addition, retrograde virus injection into the LVN led to labeling in uvula, suggesting that the LVN receives afferent input from uvula. Virus tracing revealed double-labeled neurons in the LVN following retrograde injection into the IC and anterograde injection into the uvula. Optogenetic stimulation of the LVN, electrophysiological recordings from the IC revealed a strong modulation in the firing rate of IC neurons with short latency. To investigate whether IC- projecting LVN neurons response not only to vestibular system but also to auditory stimuli, we conducted a sound exposure experiment. After sound exposure, c-fos expression in the LVN was observed in response to 8, and 32 kHz sound. This result indicates that IC-projecting LVN neurons are also activated by auditory stimulation. Taking together, these findings suggest that the LVN and IC may be functionally connected as part of a sensory-motor system.