Saccadic Eye Movement Studies

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DESCRIPTION (provided by applicant): The long-term objective of this research is to understand how the brain translates sensory information into the commands for movements. The oculomotor system is an excellent model for study because of its simple peripheral mechanics and musculature and the ease with which eye movements can be accurately measured. Because of these advantages, the component neuron types, their discharge patterns, and many of the connections of various oculomotor subsystems are comparatively well understood. Perhaps the most-studied type of eye movements is the quick, scanning movements called saccades. The specific goal of our research is to continue this detailed description in order to provide a basis for determining how the neural components actually produce saccades and to serve as a foundation for the study of higher-order neural processes. Recent studies have implicated the midline cerebellum in the direct control of saccades. Our specific aims are to begin to investigate its contribution. The major brainstem input to the cerebellum is from the nucleus reticularis tegmenti pontis (nrtp) so we will assess the function of the nrtp using recording, electrical stimulation and reversible (in) activation with neuroactive agents. We will study nrtp neurons during normal saccades and in paradigms in which the animal is required to adapt the amplitude of the saccade. We suggest that the nrtp pathway mediates feed forward and feedback control of saccades and hope to quantify this hypothesis based on the information we will provide in these studies. Because accurate eye movements are essential for clear vision, these studies contribute to our understanding of normal visual mechanisms. They also provide an example of how the nervous system processes (visual) sensory information into (saccadic) motor responses and may help to interpret studies of the intervening processes like (visual) target selection. Finally, the diagnosis and localization of nervous system dysfunction resulting from a wide variety of causes has been significantly advanced by the characterization of oculomotor functions (i.e., eye signs).