Early hearing deprivation by silicon earplugs does not alter electrophysiological development of mouse dorsal...

Rodent auditory brainstem neurons undergo substantial electrophysiological maturation during the postnatal period, spanning both pre- and post-hearing phases. These developmental adaptations support high-frequency, temporally precise neurotransmission and action potential firing. In the dorsal cochlear nucleus (DCN), fusiform neurons exhibit marked postnatal changes after the onset of hearing (postnatal day 14, P14), including refined action potential firing and the emergence of spontaneous activity. However, whether these changes are driven by acoustic input following ear canal opening remains unclear. To address this, we used a model of early hearing deprivation (EHD) in mice by inserting silicon earplugs at P14, elevating auditory thresholds by 30-40 dB, and assessed fusiform neuron electrophysiology 5-7 days later. Contrary to our hypothesis, neurons from EHD mice displayed properties similar to those of sham-treated animals. In contrast, both groups differed significantly from untreated controls, suggesting a potential influence of isoflurane anesthesia. Our findings indicate that the maturation of DCN fusiform neurons occurs independently of normal acoustic stimulation, suggesting that an intrinsic developmental program might be more relevant than experience-driven refinement.