Modeling vestibulo-ocular reflexes in everyday activities

Fundamental data for the establishment of a new clinical testing procedure for patients suffering from equilibrium disorders were developed. A mathematical model that predicts vestibulo-ocular reflex responses (eye velocities) to three-dimensional head movements was investigated. An experimental set-up permitting the simultaneous recording of the head and eye movements was developed to investigate the vestibulo-ocular reflex (VOR) during everyday activities. The test results show that computer simulation of the VOR occurring during complex movements is indeed possible. The model was able to predict the trend of the experimentally determined eye velocities. It was ascertained that for the further development of the model, the influence of the cervico-ocular reflex (COR) on the resulting eye velocities also has to be taken into account. The proposed method for investigating patients with equilibrium disorders appears suitable enough to make further development to the clinical stage worthwhile. An adaptation of the feedback amplification parameters of the model to take account of the nature of the stimulus and the influence of COR is needed to improve the agreement between the amplitudes of measured and predicted eye velocities. To reliably quantify the feedback amplification parameters, tests need to be carried out in a large number of subjects.