Figure 45.8 Hair Cells Have Mechanosensors on Their Stereocilia Hair cells have stereocilia that are connected with each other by small filaments. When a cilium is bent in one direction, the filament opens a cation channel at the tip of the neighboring cilium, resulting in depolarization of membrane potential. When depolarized, the hair cell releases neurotransmitter onto a sensory neuron. Movement of the hair cell in the opposite direction closes the cation channel and the cell hyperpolarizes, causing a reduction in its release of neurotransmitter.