Analysis of nonlinear afferent response properties from the guitarfish semicircular canal.

Nonlinear afferent response properties from the isolated guitarfish semicircular canal were investigated using a nonlinear system identification technique of combined high and low frequency rotational acceleration stimuli. Linear system unit impulse responses obtained from the dual inputs were systematically different relative to those obtained from low frequency stimuli only, implying nonlinear interactions. These results were attributed to neurophysiological mechanisms of phase locking and increased afferent excitability. A hypothesis was proposed in which similar nonlinear interactions could result from efferent activity in intact animals, suggesting that the efferents could act as a regulator of afferent response dynamics.