Effect of unilateral section of cervical afferent nerve upon optokinetic response and vestibular nystagmus induced by sinusoidal rotation in guinea pigs.

An experiment was carried out in guinea pigs to clarify the effect of unilateral section of cervical afferent nerve (C1-C3) upon optokinetic nystagmus and vestibular nystagmus induced by sinusoidal rotation. To produce optokinetic nystagmus and optokinetic after-nystagmus, a random dot pattern was utilized as visual stimulation at a speed of 30 degrees/s. As for vestibular nystagmus, sinusoidal rotation at a frequency of 0.1 Hz with an amplitude of 120 degrees was used. Results showed that for about a week after the surgical section of the C1-C3 nerves, directional preponderance of the vestibular nystagmus was found toward the lesion side, whereas no significant change was obtained in optokinetic nystagmus and optokinetic after nystagmus. This asymmetric change of the vestibular nystagmus was compensated for within a week or two. Thus. unilateral section of the cervical afferent nerve produced only a temporary effect on the vestibulo-ocular reflex but it had no significant effect on the optokinetic response.