Hair cells in the inner ear convert mechanical stimuli from sound and head movement into electrical signals that are transmitted to the brain through specialized synapses. This thesis investigated mechanisms of synaptic activity and calcium signaling at afferent and efferent synapses of vestibular bullfrog saccular and auditory chick cochlear hair cells. Using electrophysiology combined with total internal reflection fluorescence microscopy, the study examined synaptic vesicle exocytosis, voltage‑gated calcium channel activity, and cholinergic modulation. Results revealed stimulus‑dependent exocytosis, calcium‑regulated vesicle release, and distinct efferent synaptic responses across species, highlighting system‑specific mechanisms of sensory signal processing in hair cells.
