Naso-occipital vestibulo-ocular reflex responses in normal subjects

The naso-occipital translational vestibulo-ocular reflex provides a particularly difficult problem for the brain´s control system, as the movements of the two eyes are disjunctive and are often even in different directions. Consequently, when the target is located on the midline and the required eye movements are similar to vergence movements, the reflex might be driven using vergence pathways. Alternatively, the ascending tract of Deiters might be used to generate these required disjunctive movements. Since the vergence system is known to have rather sluggish dynamics, it might be possible to distinguish between these two hypotheses based on the dynamics of the movements. This article presents experiments that were undertaken in order to shed more light on these questions.