Explain how neural signals are activated and how vestibular information reaches the brain, using head rotation as the model.

Answer:

When the head rotates, the fluid (endolymph) in the semicircular canals initially lags behind the movement. This bends the cupula and the hair cells in the ampulla. Bending the hair-cell stereocilia toward the kinocilium depolarizes the cells and increases their signals, while bending them away hyperpolarizes the cells and decreases their signals. The vestibular nerve carries this information to vestibular nuclei in the brainstem and to the cerebellum, where it helps the brain coordinate balance, posture, and eye movements.