Sensory and motor aspects of saccade control.

The oculomotor reactions have recently attracted increasing attention for diagnostic purposes. This is in line with the view that the oculomotor system is one of the simpler, machine-like sensorimotor systems. This paper presents two examples to demonstrate that the complexity of sensorimotor processing may be higher than expected from the outcome of experiments under rather restricted stimulus conditions. In the first part it is shown that complex preprocessing including the evaluation of spatial gradients of visual structure is an integral part of the programming of reflex-like saccades. The second part concerns adaptivity of saccadic eye movements. The data demonstrate that saccadic gain control is highly specific to the direction of the saccade. It is suggested that many central deficits may be hidden as a consequence of the effect of specific adaptive mechanisms.