Duration of Angular Acceleration and Ocular Nystagmus from Cat and Man: I. Responses from the Lateral and the Vertical Canals to Two Stimulus Durations

Abstract

Recordings of ocular nystagmus were obtained from a group of cats and a group of human subjects to 4°/sec² angular accelerations of 8.4 sec and of 36 sec duration. Lateral canals and vertical canals were stimulated on separate trials. Results showed that the output of both primary and secondary nystagmus was greater for lateral canals. In cats, both lateral- and vertical-canal responses to the 36 sec stimuli peaked after 15–21 sec of angular acceleration and this was followed by a steady decline. Declines were not apparent in nystagmus of human subjects. A further test of these findings was conducted by manipulating arousal variables; human subjects were given special tasks and cats received d-amphetamine. Essentially the same results were obtained as described above. Other differences between the two groups were noted. Cats consistently demonstrated secondary nystagmus whereas humans did not. After termination of acceleration, primary nystagmus from cats lasted longer and exhibited a greater number of eye movements following the 8.4 sec stimulus than following the 36 sec stimulus; this consistency was not evident in humans. However, for humans the sensation of motion following termination of acceleration was of longer duration for the 8.4 sec stimulus than for the 36 sec stimulus. In this regard, nystagmus from cats resembled the subjective reactions of man more than they did the nystagmus of man.