Role of visuo-vestibular interaction in pathological ocular oscillation: new model and control system analysis.

Control system engineering is a relatively newer field of engineering which is directly applicable to performance analysis of neuronal networks. Visuo-vestibular interaction (VVI) represents a neuronal control system which has most benefited from such analysis. In this paper, we present a new model of VVI derived from our previously reported model by adding cortical pursuit feedback. Mathematical analysis of abnormal eye oscillations and stability analysis of the VVI system provided us with a plausible hypothesis that the pathological ocular oscillations seen in oculopalatal myoclonus and see-saw nystagmus are indeed due to an unstable VVI control system. The former is due to degeneration of the inferior olivary nucleus resulting in loss of cerebellar learning effects, while the latter is due to disruption of the pathway conveying retinal error signals.