Hippocampus Modulates Vocalizations Responses at Early Auditory Centers

Despite its prominence in learning and memory, hippocampal influence in early auditory processing centers re-mains unknown. Here, we examined how hippocampal activity modulates sound-evoked responses in the auditory midbrain and thalamus using optogenetics and functional MRI (fMRI) in rodents. Ventral hippocampus (vHP) ex-citatory neuron stimulation at 5 Hz evoked robust hippocampal activity that propagates to the primary auditory cortex. We then tested 5 Hz vHP stimulation paired with either natural vocalizations or artificial/noise acoustic stimuli. vHP stimulation enhanced auditory responses to vocalizations (with a negative or positive valence) in the inferior colliculus, medial geniculate body, and auditory cortex, but not to their temporally reversed counter-parts (artificial sounds) or broadband noise. Meanwhile, pharmacological vHP inactivation diminished response selectivity to vocalizations. These results directly reveal the large-scale hippocampal participation in natural sound processing at early centers of the ascending auditory pathway. They expand our present understanding of hippocampus in global auditory networks.

Automated summary

Using optogenetics and functional MRI in rodents, this study investigates how hippocampal activity modulates sound-evoked responses in the auditory midbrain and thalamus. Stimulation of ventral hippocampus excitory neurons enhances auditory responses to natural vocalizations but not to artificial sounds or noise. Pharmacological inactivation of the ventral hippocampus diminishes response selectivity to vocalizations. These findings reveal the importance of hippocampus in sound processing at early centers of the ascending auditory pathway.