My research is in visual neuroscience and computational vision, with contributions to the study of form, symmetry, flicker, motion, color, and stereoscopic depth perception in adults. We have developed tests for the diagnosis of eye diseases in infants and for retinal and optic nerve diseases in adults. Our studies of retinal diseases have addressed questions about how light is turned into electrical energy in the receptors of the retina (rods and cones) and found characteristic signatures of disease loss in retinal degenerations and in diseases of the optic nerve such as glaucoma.

Our work with electrical brain potentials and functional magnetic resonance imaging (fMRI) has revealed a rich complexity in the responses to simple stimuli, implying that we could record many different brain circuits from outside the head. We developed a rapid method of recording brain responses across a wide range of conditions (the "sweep VEP"), which could then be used to study infant vision. The short recording time required by this new method allowed us to measure visual development with great accuracy..We found that infants can see much better at birth than previously suspected, and have close to adult vision by about eight months of age (although they may not fully "understand" what they see at this age). We can also detect the effects of poor eye coordination more readily than could previous techniques, and help physicians refine the treatment of infant eye problems.

My current emphasis is on new techniques of brain imaging that allow high-resolution mapping of the response in each local brain region in order to detect and understand the meaning of the vast array of images arriving at the eyes. Each class of images--motion, form, color, depth, symmetry and so on, activates a different circuit of brain tissue. We hope these discoveries will provide the basis for understanding the losses experienced by patients with neurological deficits in the visual part of the brain.

For more information, visit Chris Tyler's lab web pages.

Collaborators: Leonid Kontsevich, Lora Likova, Alex Wade, Chien-Chung Chen, Stan Klein, Thom Carney.