Table 1.
A list of all implanted canals of four rhesus monkeys, the status of whether vestibular ECAPs were detectable (>50 µV in N1-P1 amplitude growth), and the primary direction of eye movements that reached a minimum velocity criterion (>20 degree/sec).
| Animal | Implanted Canals | ECAP1 | Eye Movements2 |
|---|---|---|---|
| Monkey A | Lateral | Yes | Horizontal |
| Posterior | Yes 3 | Vertical | |
| Monkey B | Lateral | Yes | Horizontal |
| Monkey C | Lateral | Yes | Horizontal |
| Superior | No | None 4 | |
| Monkey D | Lateral | No | None |
| Posterior | No | None |
A minimum N1-P1 amplitude of 50 µV was adopted as threshold for indicating the presence or absences of an ECAP.
A threshold velocity of 20 dec/sec was used for determining the presence of an EEM.
High-amplitude stimulus artifacts were recorded when the stimulating and recording electrodes were both in the posterior canal. However, ECAP waveforms were observed when stimulating in the posterior canal and recording in the lateral canal.
Subthreshold EEM nystagmus could only be observed at high current levels that were close to the maximum limit of the device output.