This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To understand how higher order processes or cognition contribute to the control of voluntary movement. Because the execution of voluntary actions usually involves processes such as target selection, learning, memory, planning and expectation, motor systems are well suited for study of these processes. We investigate neuronal processes leading up to the execution of movements of the eyes, in particular, those eye movements that lead to rapid changes in the line of sight - saccades. We have a multi-technique approach to the study of these processes. First, we record electrical activity of single neurons while the subjects perform eye movement tasks designed to tap into cognitive processes. Second, we activate or inactivate particular regions of the brain to produce behaviors or interfere with ongoing behaviors and neural processing. Finally, because damage to certain brain regions produces profound clinical disorders such as Parkinson's disease and Huntington's disease, we study eye movements of both healthy and diseased human subjects to further our understanding of the role these structures play in both cognition and in producing the debilitating effects of these disorders. This research used WNPRC Animal Services.