Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

Stuart Leigh Johnson (1) , Tobias Eckrich (1) , Stephanie Kuhn (1) , Valeria Zampini (1) , Christoph Georg Franz (1) , Kishani Mangika Ranatunga (1) , Terri Patricia Roberts (1) , Sergio Masetto (1) , Marlies Knipper (1) , Corne J. Kros (1) , Walter Marcotti (1)

1 Biomedical Science

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion cells and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials are intrinsically generated by immature IHCs of altricial rodents and that apical IHCs exhibit bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter ACh, by fine-tuning the IHC's resting membrane potential (), is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the of apical and basal IHCs by activating SK2 channels. We hypothesize that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

Mots clés: Sensory Systems; Channels; Development; Neurophysiology

Stuart Leigh Johnson, Tobias Eckrich, Stephanie Kuhn, Valeria Zampini, Christoph Georg Franz, et al.. Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells. Nature Neuroscience, 2011, ⟨10.1038/nn.2803⟩. ⟨hal-00641192⟩