Efferent feedback controls bilateral auditory spontaneous activity

In the developing auditory system, spontaneous activity generated in the cochleae propagates into the central nervous system to promote circuit formation. The effects of peripheral firing patterns on spontaneous activity in the central auditory system are not well understood. Here, we describe wide-spread bilateral coupling of spontaneous activity that coincides with the period of transient efferent modulation of inner hair cells from the brainstem medial olivocochlear system. Knocking out alpha 9/alpha 10 nicotinic acetylcholine receptors, a requisite part of the efferent pathway, profoundly reduces bilateral correlations. Pharmacological and chemogenetic experiments confirm that the efferent system is necessary for normal bilateral coupling. Moreover, auditory sensitivity at hearing onset is reduced in the absence of pre-hearing efferent modulation. Together, these results demonstrate how afferent and efferent pathways collectively shape spontaneous activity patterns and reveal the important role of efferents in coordinating bilateral spontaneous activity and the emergence of functional responses during the prehearing period. Spontaneous activity generated in the cochleae propagates into the central auditory system to promote circuit formation before hearing onset. Here, the authors reveal the important role of cholinergic efferent modulation in coordinating bilateral spontaneous activity and the emergence of functional responses.

Automated summary

Research reveals the crucial role of cholinergic efferent modulation in coordinating bilateral spontaneous activity and the emergence of functional responses in the developing auditory system. The efferent pathway is essential for normal bilateral coupling and coordination during the prehearing period.