title: The effects of ageing on stereopsis. A VEP study.
abstract: Differences in brain activation between young (n = 11, ages 21-35) and elderly (n = 8, ages 70-84) healthy participants were studied using visual evoked potentials (VEPs) to different kinds of computer generated random-dot patterns. The main stimulus of interest was a 2 x 2 array of rectangles whose rectangles moved to and fro in depth. Control conditions were similar 2 x 2 arrays, one with side-to-side lateral motion (LM) of the rectangles, and one a stationary baseline condition. The third non-stereo stimulus was an expanding field of small dots in radial motion (RM). Significant stereo related activation was found in both age groups. The stereo VEPs showed a longer latency of depth reversal triggered VEP peaks compared to control LM VEPs. The amplitudes of LM VEPs were larger than the baseline VEPs. Age-related differences were found not only in stereo but also in the other conditions. Thus the latency of early VEP peaks was shorter and their amplitude higher in the elderly for LM and baseline conditions, and the younger participants showed significantly higher activation in the later VEP peaks of all conditions. Our main finding is no evidence for age related stereo specific effects in brain activation, but instead more general and subtle changes that affect widely different visual stimulus conditions.
authors.affiliation: Department of Psychology, University of Sheffield, Sheffield S10 2TP, UK. n.a.taroyan@sheffield.ac.uk
authors.forename: Naira A
authors.initials: NA
authors.lastname: Taroyan
authors.forename: Subha
authors.initials: S
authors.lastname: Thiyagesh
authors.forename: Laurence
authors.initials: L
authors.lastname: Vigon
authors.forename: David
authors.initials: D
authors.lastname: Buckley
authors.forename: Peter W R
authors.initials: PW
authors.lastname: Woodruff
authors.forename: Claire
authors.initials: C
authors.lastname: Young
authors.forename: Reza
authors.initials: R
authors.lastname: Saatchi
authors.forename: John P
authors.initials: JP
authors.lastname: Frisby
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003867:Depth Perception / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male