Research Interests

Dr. Snodderly's core interest is the study of vision. He does research on the effects of nutrition on the eye, with particular emphasis on the retina. He is interested in the effects of aging on visual function and the potential for nutrition to slow or to prevent age-related diseases such as cataract and macular degeneration. Together, these entities are the leading causes of blindness in the world and in the USA. Dr. Snodderly began his career with bachelor's and master's degrees from MIT in electrical engineering, followed by a doctorate in biology from the Rockefeller University and postdoctoral training in psychology at the University of California, Berkeley. He combines approaches from each of these disciplines in his research.

Current research on the retina focuses on the role of the macular pigment carotenoids that are thought to protect the primate fovea from damage by light. These pigments are derived from the diet and they confer the characteristic yellow color that bestows the name, macula lutea, on the foveal region. To study humans, he and his collaborators have developed psychophysical (perceptual) techniques that are noninvasive and permit investigations utilizing large numbers of subjects. Efforts are focused on making the psychophysical measurements of macular pigment easy and robust so that they can be used with elderly subjects who either have macular degeneration or are at risk for it. Measures of visual function are emphasized that should be sensitive indicators of age- related or disease-related changes in the retina. These include procedures that tap the S-cone pathways of the retina, such as increment thresholds, silent substitution, and chromatic cancellation.

Another project is the study of coding of information by neurons in the visual pathway. Recordings are made of electrical activity of neurons in the lateral geniculate nucleus and the visual cortex of alert, trained monkeys. These are basic studies designed to discover the neural mechanisms that make vision such an important asset. Experiments will emphasize the ways that visual aspects of the natural environment are coded by neurons in the visual pathway, including the influence of eye movements. Many people have theorized that important aspects of primate vision have evolved in response to selection pressures related to foraging for food, and this proposal will be tested as part of the research program.

Dr. Snodderly's research involves collaborators at several other universities who contribute a diversity of talents and insights to the work.

Selected Recent Publications

Snodderly DM. Evidence for protection against age-related macular degeneration (AMD) by carotenoids and antioxidant vitamins. Am J Clin Nutr. 1995; 62 (Suppl): 1448S-1461S.

Snodderly DM, Gur M. Organization of striate cortex (V1) of alert, trained monkeys (Macaca fascicularis): Ongoing activity, stimulus selectivity, and widths of receptive field activating regions. J Neurophysiol. 1995; 74:2100-2125.

Snodderly DM, Hammond BR. In vivo psychophysical assessment of nutritional and environmental influences on human ocular tissues: Lens and macular pigment. In: Taylor, A, ed. Nutritional and Environmental Influences on Vision. Boca Raton: CRC Press, 1999.

Snodderly DM, Kagan I, Gur M. Selective activation of visual cortex neurons by fixational eye movements: Implications for neural coding. Vis Neurosci. 2001; 18: 259-277.

Kagan I, Gur M, Snodderly DM. Spatial organization of receptive fields of V1 neurons of alert monkeys: comparison with responses to gratings. J Neurophysiol. 2002; 88: 2557-2574.

Snodderly DM, Mares JA, Wooten BR, Oxton L, Gruber M, Ficek T. Macular pigment measurement by heterochromatic flicker photometry in older subjects: the Carotenoids and Age-Related Eye Disease Study. Invest Ophthalmol Vis Sci. 2004; 45: 531-538.

Leung IY-F, Sandstrom MM, Zucker CL, Neuringer M, Snodderly DM. Nutritional manipulation of primate retinas, II. Effects of age, n-3 fatty acids, lutein, and zeaxanthin on retinal pigment epithelium. Invest Ophthalmol Vis Sci. 2004; 45: 3244-3256.

Johnson EJ, Neuringer M, Russell, RM, Schalch W, Snodderly DM. Nutritional manipulation of primate retinas. III. Effects of lutein or zeaxanthin supplementation on adipose and retina of xanthophyll-free monkeys. Invest Ophthalmol Vis Sci. 2005; 46: 692-702.

Gur M, Kagan I, Snodderly DM. Orientation and direction selectivity of neurons in V1 of alert monkeys: functional relationships and laminar distributions. Cereb Cortex. 2005; 15: 1207-1221.

Leung IY-F, Sandstrom MM, Zucker CL, Neuringer M, Snodderly DM. Nutritional manipulation of primate retinas. IV. Effects of n-3 fatty acids, lutein, and zeaxanthin on S-cones and rods in the foveal region. Exp Eye Res. 2005; 81: 513-529.

Gur M, Snodderly DM. High response reliability of neurons in primary visual cortex (V1) of alert, trained monkeys. Cereb Cortex. 2006; 16: 888-895.

Stringham JM, Hammond BR, Wooten BR, Snodderly DM. Compensation for light loss due to filtering by macular pigment: Relation to the -1 mechanism. Optom.Vis.Sci. 2006; 83: 887-894.

Mares JA, LaRowe TL, Snodderly DM, Moeller SM, Gruber MJ, Klein ML, Wooten BR, Johnson EJ, Chappell RJ. Predictors of optical density of lutein and zeaxanthin in retinas of older women in the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women's Health Initiative. Am J Clin.Nutr. 84: 1107-1122, 2006.

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