Professor Emeritus Optometry and Vision Science
School of Optometry
Single Cone Psychophysics
We are using Austin Roorda’s adaptive optics scanning laser ophthalmoscope (AOSLO) for human psychophysics (for details go to Roorda’s information). The AOSLO has the capability of stimulating individual cones repeatedly, with the ability to go to the same cones over years. AOSLO’s unique capabilities enable us to learn about fine-grained spatio-temporal-chromatic nonlinear visual processing that was previously not available for investigation. Only three such instruments are presently available, one at UCSF for clinical research, one in Alabama for primate research and the one at Berkeley used for normal humans. The full single cone capability of these instruments has only been realized in 2012, so this collaborative research is in its exciting pioneering stage.
Modeling of Spatial Vision
The visual system is assumed to consist of an enormous number of spatial filters with different positions, sizes, orientations and bandwidths. These filters are arranged in sequential stages with nonlinear interactions between and within the stages. In our laboratory, we do psychophysical experiments to learn about the multiple stages of visual processing. Our recent research has explored the role of perceptual learning, attention and binocular interactions.
Nonlinear Systems Analysis with Application to Localizing VEP Sources
The use of fMRI and MRI scans for imaging brain activity has created much excitement among brain researchers. We have developed a new approach that combines nonlinear analysis, MRI, fMRI and the visual evoked potential (VEP) should reveals the underlying neural generators of visual cortex with a temporal resolution 100-1000 times better than is possible with fMRI.