Compensatory eye movements in mice

This thesis will address the generation of compensatory eye movements in naturally mutated or genetically modified mice. The reason for generating compensatory eye movements is solely related to the requirements for good vision. In a subject moving through its environment the projection of visual surround would slip across the retina and retinal slip of more than only a few degrees per second would cause blurring of the projected image and reduce visual acuity (Westheimer and McKee, 1975). Compensatory eye movements are therefore generated to assure that visual projections on the retina remain at approximately the same retinal coordinates, thereby preserving a stable image despite perturbations due to self-generated or imposed movement of the head. Because of its relative simplicity the oculomotor system, which encompasses the entire transformation from sensory input to the generation of compensatory eye movements, has served as a particularly useful model for physiologists who try to understand how the brain controls movement. The repertoire of possible movements in the oculomotor system is limited to those of the eyeball in its socket, which constitutes a single joint on which three pairs of extra-ocular muscles exert their force. Each pair of muscles affects movement around one of three orthogonal rotational axes and due to a fairly constant mechanical load on the eye muscles no stretch reflex is needed. This relative simplicity of the oculomotor system and the fact that both behavioral output and sensory input can be readily measured makes it amenable to detailed quantitative analysis