Nonlinear Dynamics of the Auditory System: Insights from the Amphibian Papilla

The auditory system's remarkable sensitivity, capable of detecting displacements as small as 3 Å and frequencies up to 200 kHz, is largely attributed to active amplification by sensory cells. This study investigates the nonlinear dynamics of hair cells in the bullfrog's amphibian papilla, employing a robust ex vivo preparation to observe both spontaneous and driven oscillations. Preliminary results reveal significant variation in the characteristics of spontaneous oscillations, including diverse amplitudes, frequencies, and bursting behavior, suggesting multiple bifurcations in the underlying dynamics. Individual hair cells demonstrate phase locking to weak signals and exhibit compressive nonlinearity akin to in vivo responses. Our ongoing research aims to further elucidate the nonlinear dynamics of the auditory system, with a particular focus on frequency tuning and tonotopy in the amphibian papilla. This study describes auditory detection as a complex interplay between nonlinear dynamics and out-of-equilibrium physics, enhancing our understanding of sensory perception mechanisms.