Our laboratory studies how visual perception and cognition guide the smooth pursuit eye movement system. The goal of our research is to provide information about basic neural mechanisms that drive this system that will aid in the diagnosis and treatment of vision and eye movement disorders. Basic knowledge about brain function obtained through this work should generalize to help better understand devastating disorders that affect movement and perception such as schizophrenia, Parkinson's, and Alzheimer's diseases.
This project investigates the properties of smooth pursuit eye movements in individuals with macular degeneration. Commonly believed to be a fovea-linked eye movement, smooth pursuit has not been previously investigated in individuals with central field loss, despite its importance for tracking moving objects, such as vehicles or pedestrians on a busy street.
The decision to make or withhold a saccade has been studied extensively using a go-nogo paradigm, but little is known about the decision process underlying pursuit of moving objects. Prevailing models describe pursuit as a feedback system that responds reactively to a moving stimulus. However, situations often arise in which it is disadvantageous to pursue, and humans can decide not to pursue an object just because it moves. This project explores mechanisms underlying the decision to pursue or maintain fixation. Our paradigm, ocular baseball, involves a target that moves from the periphery toward a central zone called the "plate".
Traditionally, smooth pursuit research has explored how eye movements are generated to follow small, isolated targets that fit within the fovea. Objects in a natural scene, however, are often larger and extend to peripheral retina. They also have components that move in different directions or at different speeds (e.g., wings, legs). To generate a single velocity command for smooth pursuit, motion information from the components must be integrated. Simultaneously, it may be necessary to attend to features of the object while pursuing it.