Visual behavior is performed by an animal in its environment using its eyes, its brain, and locomotion. The horseshoe crab, Limulus, provides a powerfully simple system for investigating vision. Although there is a classic quantitative model for how the lateral compound eye of Limulus works, the neural coding that mediates visual behavior remains unknown. This project investigates the role of identifiable single nerve cells in processing visual information that lead to simple motor behavior, such as turning toward an interesting target. Behavioral studies in the field allow estimates of visual acuity, contrast sensitivity and object recognition. Novel methods for nerve cell recording in the natural underwater environment allow alalysis of optic nerve responses during behavior to see what information might be carried to the brain. Intracellular recording of identifiable nerve cells in the brain during visual activity allows analysis of how the brain processes information coming from the eye. Results from this remarkably integrative study will clarify how sensory signals relate to behavior. Findings will have an impact not only on visual neuroscience and neuroethology, but also on computational neural modeling, evolutionary and comparative biology, and robotics.
