Computational Model of Ephaptic Coupling and Potassium Modulation at the Vestibular Hair Cell Calyx Synapse

Abstract

Sensory hair cells of the vestibular inner ear detect and relay information on head motion to afferent neurons, which in turn guide motor reflexes that maintain gaze, balance, and our sense of orientation. Afferent neurons form large cup-shaped synaptic terminals (calyces) on type I hair cells that transmit to calyces by both quantal (Q) release of glutamate from vesicles and non-quantal (NQ) flow of ions from the hair cell into the synaptic cleft and the postsynaptic calyx. The measurement of ion concentrations and electric potentials within the synaptic cleft is difficult and has been a barrier to understanding NQ transmission.