Physiological localization of the semicircular canal receptors in the crista.

Isolated posterior semicircular canals from the bull frog model were used. The cupula was removed from the crista and the sensory cilia on the crista were depressed toward the canal side by using a glass micropipette. Seven different points were selected for stimulation on the ampullary wall. Ampullary nerve action potentials induced by depression were recorded and were converted into spike-density histograms. Response decremental time constants were measured on these histograms. The longest time constant was measured at the two lateral points of stimulation and progressively shortened toward the central point of stimulation. These results indicate that the origin of the adaptation is possibly sensorineural.