FIG. 1.

General experimental setup. Top: expanded view of the labyrinth. Bottom: overview of the fish. A current-passing electrode (I_e) is placed in the posterior limb of the anterior canal and a second voltage-measuring electrode (V_e) placed in the anterior canal ampulla for applying and recording electrical polarization stimuli, respectively. Mechanical stimulation of the horizontal semicircular canal is provided by a piezo electrically driven indenter placed on the long and slender limb of the canal duct (HCI); this mode of canal activation can be tailored to closely mimic head rotation but can be applied independent of head movement in space. Extracellular afferent records (V_n) were obtained simultaneously with the applied stimuli. A small hole was made in the utricular side of the horizontal canal ampulla for access to the sensory epithelium by sharp electrodes to record hair cell receptor potentials or currents during canal indentation or polarization or a combination of the 2 stimuli.