Time: 14:00-15:30  on Wed., May. 9,?2018

Venue: 143, Life Sciences Building, Tsinghua University

Speaker：Dr. Ruth Anne Eatock, Dean, Faculty Affairs, Biological Sciences, University of Chicago

Host: Dr. Wei Zhang, PI, IDG/McGovern Institute, Tsinghua University

Title: Non-quantal and quantal mechanisms of transmission across hair cell-calyx synapses in the vestibular inner ear

Abstract: The sensory epithelia of the vestibular inner ear supply signals about head motions to fast reflexes that stabilize balance and gaze as the head moves. The vestibular epithelia of reptiles, birds, and mammals (amniotes) have unusual calyceal synapses between hair cells and afferent neurons. Transmission occurs by two mechanisms at these calyceal synapses, one quantal and one non quantal. The quantal mechanism is shared by all hair cells and involves release of glutamate from vesicles (quanta) arrayed at ribbon synapses. The non-quantal mechanism is unique to the hair cell-calyceal synapses and depends on ion currents through voltage-sensitive ion channels on presynaptic (hair cell) and postsynaptic (calyceal) membranes. The two mechanisms shape mechanosensory signals differently – notably, the non-quantal mechanism has negligible synaptic delay. These and other specialized features of amniote hair cells and afferents may have evolved in response to the challenges of maintaining balance and gaze during locomotion on land.