UC San Diego

The vestibular system is critical for postural balance, orientation, reflexive control of eye movements, and spatial cognition, yet compared with other sensory systems little is known about its cellular basis. Head motion signals are transduced in the inner ear and carried to brainstem vestibular nuclei by vestibular nerve afferents. The nature and quality of head motion information in the central nervous system depend on the capacity of vestibular nerve synapses to influence firing in postsynaptic neurons. This dissertation examines the functional and molecular features of the vestibular nerve synapse that promote the faithful transmission of head motion signals. Experimental results revealed that these synapses are specialized to provide postsynaptic neurons with unambiguous signals that linearly relate to head velocity. Extensive refinements of cellular machinery enable reliable, fast, linear synaptic transmission while still allowing for modifications of synaptic strength. Long-term depression and potentiation of vestibular nerve synapses linearly regulate the firing responses of postsynaptic neurons and are well suited to underlie cerebellum-dependent calibration of vestibular reflex strength