Parvalbumin and Somatostatin: Biomarkers for Two Parallel Tectothalamic Pathways in the Auditory Midbrain

作者：Mengting Liu, Yixiao Gao, Fengyuan Xin, Ying Hu, Tao Wang, Fenghua Xie, Chengjun Shao, Tianyu Li, Ningyu Wang, Kexin Yuan · 发表于：Journal of Neuroscience · 年份：2024 · DOI：10.1523/jneurosci.1655-23.2024 · 被引用次数：13 · 研究领域：Hearing, Cochlea, Tinnitus, Genetics、Neural dynamics and brain function、Neuroscience and Neuropharmacology Research

The inferior colliculus (IC) represents a crucial relay station in the auditory pathway, located in the midbrain's tectum and primarily projecting to the thalamus. Despite the identification of distinct cell classes based on various biomarkers in the IC, their specific contributions to the organization of auditory tectothalamic pathways have remained poorly understood. In this study, we demonstrate that IC neurons expressing parvalbumin (IC PV+ ) or somatostatin (IC SOM+ ) represent two minimally overlapping cell classes throughout the three IC subdivisions in mice of both sexes. Strikingly, regardless of their location within the IC, these neurons predominantly project to the primary and secondary auditory thalamic nuclei, respectively. Cell class-specific input tracing suggested that IC PV+ neurons primarily receive auditory inputs, whereas IC SOM+ neurons receive significantly more inputs from the periaqueductal gray and the superior colliculus (SC), which are sensorimotor regions critically involved in innate behaviors. Furthermore, IC PV+ neurons exhibit significant heterogeneity in both intrinsic electrophysiological properties and presynaptic terminal size compared with IC SOM+ neurons. Notably, approximately one-quarter of IC PV+ neurons are inhibitory neurons, whereas all IC SOM+ neurons are excitatory neurons. Collectively, our findings suggest that parvalbumin and somatostatin expression in the IC can serve as biomarkers for two functionally distinct, parallel tect...