A computational model of the mammalian auditory periphery with a closed-loop medial olivocochlear reflex simulating across-channel efferent gain control.

The afferent (ascending) auditory system and how its specialized mechanisms and circuits support ecologically relevant auditory computations such as speech recognition have received considerable attention in decades past. This work has culminated in accurate computational models of early afferent coding alongside a good understanding of how low-level mechanisms (e.g., peripheral tuning) impact auditory perception. In contrast, the auditory efferent (descending) system and its role in auditory perception are much less well understood. To address this gap in knowledge, we describe modifications to a model of the auditory periphery to include the medial olivocochlear efferent reflex pathway. Neurons in this pathway respond to sound and make descending projections to outer hair cells that reduce cochlear gain in a reflex-like loop. Our model of this system differs from existing models primarily in its multichannel design, which is intended to simulate the consequences of tonotopically distributed control of outer hair cells by individual medial olivocochlear neurons. We show that this model can simulate the frequency-specific sensitivity and strength of the effects of contralateral elicitors on auditory-nerve responses, including especially the effect of elicitors that are tonotopically distant from probes.