Figure 5.

Multi-unit inferior rectus (IR) nerve discharge during activation of native bilateral semicircular canals and a transplanted third ear on the spinal cord. (A) Schematic of a semi-intact Xenopus preparation depicting the recording of the right IR nerve during roll motion (black curved double arrow), galvanic vestibular stimulation (GVS) of the contralateral posterior (cPC) and iAC semicircular canal epithelia (iAC; red electrodes) and of the transplanted third ear (green electrodes). (B) Episode of spontaneous IR nerve discharge (black trace) with an average resting rate of ~20 spikes/s (blue trace) in an isolated preparation obtained from a stage 55 tadpole. (C, E, G) Modulated multi-unit discharge (black traces) and mean firing rate (lower colored traces) of the same IR nerve during roll motion in the cPC-iAC plane (C), during GVS of the cPC-iAC (E) and during GVS of the third ear (G); sinusoids indicate the waveform (1 Hz) for natural and galvanic stimulation. (D, F, H) Modulated mean IR nerve firing rate over a single cycle (black traces) ± SEM (color-shaded areas) of the responses shown in C,E,G; the averages were obtained from 20–120 single cycles, respectively; the colored dotted sinusoids indicate the motion stimulus (D) and GVS of the cPC (F) and third ear (H), and the blue dashed line and horizontal band the mean ± SEM resting rate of the IR nerve. Note that the IR nerve increases firing during motion in direction of the cPC (D), galvanic depolarization of the cPC epithelium (F) and galvanic depolarization of the third ear (*in G, H). T_pos, position signal of the turntable. [Colour figure can be viewed at wileyonlinelibrary.com]