NORTH DAKOTA STATE UNIVERSITY
Project Goals. We are using a powerful new paradigm, the quadrature-phase motion technique to measure the magnitude of both luminance-based first-order (Grating Induction) and contrast-based second-order (Contrast-Contrast) inhibitory visual processes over a large range of spatial and temporal frequencies, at multiple retinal eccentricities, to assess age-related alterations in spatiotemporal inhibitory processing. We hope that our findings may be translatable to the development of a useful diagnostic clinical test to simply and efficiently assess the status of visual inhibitory processes across the lifespan. The specific aims of the project are:
1) To compare and contrast the degree of both first- and second-order inhibitory visual processing as a function of age (18-90 years); and
2) To use the data so obtained as the foundation for an R01 proposal to further explore the effects of aging on inhibitory visual processing, and to critically examine and evaluate the feasibility of developing the quadrature-phase motion paradigm into a clinically-useful diagnostic test to assess age-related changes in visual inhibitory processing.
We have recruited and tested over 100 subjects, ranging in age from 16-76. We have thus far only tested first-order induction effects.
Research highlights include:
1) Evidence that the lower visual field is differentially affected by the aging process, such that significantly greater contrast is required for a grating in the lower visual field to appear the same as a grating in the upper visual field. The lower visual field is very important in locomotion, and compromised visual function in the lower visual field might be one cause of loss of balance and falling.
2) Evidence that first-order induction decreases significantly with age for counterphase temporal frequencies of 4 Hz, whereas age-related decline is not observed at frequencies of 1 Hz .