SACCADIC EYE MOVEMENT STUDIES

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DESCRIPTION: (Adapted from the Investigator's Abstract) The long term objectives of the this research is to understand how the brain translates sensory information into the commands for movement. The oculomotor system is an excellent model for study because the peripheral mechanics and musculature are fairly well understood and eye movements can be accurately recorded. Because of these advantageous, the component neuron types, their discharge patterns and many of the connections of various oculomotor subsystems are comparatively well understood. The specific aim of this research is to continue to study the quick scanning eye movements called saccades. Although many neuron classes associated with saccadic generation have been studies extensively, the function of some neuron classes have not yet been identified. Neither has the neural substrate for several signals associated with saccadic function been identified. One focus of the study will be on a class of long lead burst neurons (LLBN's) which are posited to play a role in the implementation of the an important internal feedback signal that controls saccades. It is proposed to characterize the discharge patterns of these LLBN's in relation to saccades, map their exact location, distinguish any subgroups and test their function by (in)activation with neuroactive agents. The proposed analysis will test a number of hypotheses for the role of LLBN's in saccadic function. Another focus of the proposed studies will be to confirm preliminary identification of the feedback signal from the pons to superior colliculus, begin to trace the neural pathways that mediate it, and how it contributes to saccadic generation. Because accurate eye movements are essential for clear vision and because oculomotor commands derive from visual input, these studies should contribute to our understanding of normal visual mechanisms. These studies should provide an example of how the nervous system processes (visual) sensory information into (saccadic) motor responses and may help to interpret studies of intervening processes like (visual) target selection. Finally, the diagnosis and localization of nervous system dysfunction resulting from a wide variety of causes has been and will be significantly advanced by the identification of the saccadic functions of different brain areas because of the facility with which eye movements can be accurately recorded.