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. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: Cochlear Implants Int. 2010 Sep;11(Suppl 2):2–11. doi: 10.1179/146701010X12726366068454

Figure 3.

Figure 3

Eye movement responses to pulse-rate modulated, biphasic constant-current pulses delivered via monopolar prosthesis electrodes implanted in the left labyrinth of a stationary alert rhesus monkey tested in darkness. Methods for stimulus delivery and scleral coil recording of eye movements are as described in (Dai et al., 2010). Lower traces show stimulus waveforms modulating pulse rates on electrodes in the left horizontal (LZ), left anterior (LA) and left posterior (LP) semicircular canal ampullary nerves. In each case, modulation frequency is 5 Hz (i.e., encoding a 5 Hz virtual head rotation about the axis of the stimulated canal), baseline pulse rate is 100 pulse/sec, and the three different stimulus intensities shown represent 40%, 60% and 80% of maximum possible pulse frequency modulation depth. (At 100% intensity, pulse rate would modulate down to 0 and up to 400 pulse/sec.) Upper traces show eye movements about the horizontal (Z), left-anterior/right-posterior (LARP), and right-anterior/left-posterior (RALP) axes of the head, which approximately align with the implanted semicircular canals. Slow phase nystagmus segments are black; saccades, quick phases and blinks are shown in gray. Stimulation via each canal’s electrode generates eye movements that approximately align with that canal.