Improved algorithm for classification of ocular nystagmus

Primate disconjugate eye movements during the horizontal AVOR in darkness and a plausible mechanism

Disconjugate eye movements during the horizontal angular vestibulo-ocular reflex (AVOR) evoked in response to steps or pulses of head velocity have been previously reported in lateral eyed animals. In this study, we measured binocular responses to sustained sinusoidal and pseudo-random vestibular stimuli in yaw, delivered in darkness, in both human and monkey. The vestibular stimuli used in our experiments had peak velocities in the range of 120-200 degrees /s, frequencies in the range of 0.17-0.5 Hz, and durations between 60 and 75 s. Our results show a large vergence component to the AVOR response that systematically modulated with head velocity. We also examined our results for temporal-nasal preponderance in slow eye velocity. Although each subject showed some degree of directional preference, we did not find a systematically greater eye velocity for temporal-nasal direction across all subjects. Here, we present these findings and discuss that at least two possible sources could result in disconjugate eye movements during the horizontal rotational VOR in darkness: peripheral and central mechanisms.

Modulation of vergence during the vestibulo-ocular reflex

It is commonly believed that during the compensatory slow-phases of the vestibulo-ocular reflex (VOR), eyes move in a perfectly conjugate fashion (i.e. the vergence component is zero). Consequently, VOR measurements are often restricted to either conjugate recordings or to single eye recordings. During binocular recordings of the angular VOR in the dark, we observed a significant vergence component even in normal subjects. More interestingly, the measured vergence component modulated with head velocity. The modulation of vergence during the VOR in the dark could imply a vestibular contribution to vergence. These observations suggest a shared central controller for both version and vergence.