Genetic and functional diversity of primary auditory afferents

Type I spiral ganglion neurons (I-SGNs) of the mammalian cochlea convey all acoustic information from the sensory hair cells to second order neurons in the brainstem. Despite evidence supporting physiological diversity of I-SGNs and of its importance for encoding the various features of sounds, knowledge of their molecular diversity is only emerging. In this review, we outline the recent efforts in the identification of mammalian I-SGN types and summarize how genetic and anatomical features of each individual neuron type relate to functional aspects that characterize sound information processing in the primary auditory afferent system.