Development, validation, and sensitivity analyses of human eye movement models.

A, Why the Ocular Motor Systems? The ocular motor systems are ideal for studying the control of human movement. Eye movements are easy to measure, and the control of saccadic eye movements is simpler than the control of other neuromuscular systems. It is simpler because the load presented by the eyeball and extraocular tissues is small and constant. Horizontal eye movements offer a further simplification because they primarily involve only two muscles of each eye. By scrutinizing the trajectories of saccadic eye movements, we can infer the motoneuronal activity, deduce the central nervous system's control strategy, and observe changes in this control strategy caused by fatigue, alcohol, drugs, or pathology. These eye movement control principles should generalize to other neuromuscular systems. There are two additional reasons for choosing the eye movement control systems as a model for neuromuscular control. First, we can present the development of a model by 11 authors over a span of more than 25 years (see Table 1). Second, an in-depth evaluation of this final model can be presented. The study of eye movement control models was chosen not because eye movements are thought to be so important, but rather because the physiological system is simple and typical and the models are well studied.1