Figure 2. Overview of the Labyrinth Devices MVI and study.

(A) The MVI stimulator comprises 3 fixation magnets, an inductive coil link, electrical current stimulator circuitry, stimulation electrode array, a stimulation reference electrode, and a recording reference electrode. The electrode array includes a 3-electrode shank for the (B, E3–E5) posterior canal, a forked subarray with 2 shanks for the (C, E6–E8) horizontal, and (D, E9–E11) anterior canals, and a stimulation reference electrode. (E) Surgical diagram illustrating electrode implantation sites, comprising surgical openings drilled in each of 3 canal ampullae and the common crus of 1 labyrinth. (F) The head-worn unit (HWU), magnetically coupled to subject MVI001’s scalp over his implanted stimulator, houses a 3D motion sensor and inductively supplies power and control signals to the implant. (G) The power and control unit (PCU, hanging on lanyard) houses a battery and control circuity. A Labyrinth Devices 3DBinoc video-oculography system (top) records horizontal, vertical, and torsional components of 3D eye position during VOR responses to natural and/or prosthetic stimulation. (H) Example 3D head velocity waveforms (corresponding to vectors in Figure 1D) modulate MVI pulse rate and amplitude. Input waveforms can be either actual head motion sensed by the HWU or synthetically generated by MVI fitting software. (I) Example pulse rate and amplitude modulation maps for each left ear canal. Top image portrays head velocity to pulse rate map; lower plot displays maps for pulse amplitude. Maps use non-zero pulse rate and current amplitude for 0°/s to evoke neural activity mimicking spontaneous afferent neuron discharge (dashed lines). The MVI encodes excitatory and inhibitory head motions via coordinated up- and downmodulation of pulse rate and amplitude (J and K). (L) This is an open-label, nonrandomized, early feasibility study of applicants self-identified as potential trial candidates. Reproduced by permission from Labyrinth Devices, LLC, ©2019.