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. A central goal of visual neurophysiology is to understand the relationship between light entering the eye and the electrical responses of neurons in visual cortex. It has long been known, for example, that many visual cortical neurons respond selectively to lights of particular wavelength compositions. The precise relationship between the wavelength composition of a particular light and the neural response that the light evokes, however, has remained elusive. The goal of this project is to derive a mathematical model that accounts for the responses of visual neurons to various lights.