The effect of senescence on orientation discrimination and mechanism tuning

Peter B. Delahunt, Joseph L. Hardy, John S Werner

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Accurately processing orientation information is a fundamental component of visual performance. Single-unit recordings have shown that the orientation tuning of individual neurons in macaque cortical areas V1 and V2 is reduced dramatically with age (M. T. Schmolesky, Y. Wang, M. Pu, & A. G. Leventhal, 2000; S. Yu, Y. Wang, X. Li, Y. Zhou, & A. G. Leventhal, 2006). These researchers suggest that losses in single-unit orientation 'selectivity result, in declines in orientation discrimination and object recognition in older humans. Three experiments were conducted to determine whether human performance is affected by putative age-related changes in tuning of cortical neurons. Ten younger and ten older observers participated in this study. Experiment 1 demonstrated significant differences in the contrast sensitivity of the two age groups. Experiment 2 showed significant differences in orientation discrimination thresholds. However, when thresholds were plotted in terms of multiples of detection threshold, age-related differences were not observed. In Experiment 3, perceptual orientation tuning curves did not significantly differ in shape for younger and older subjects. As in Experiment 2, at any given contrast, there is a large difference in sensitivity between younger and older adults. This implies a model of orientation processing that allows the adult visual system to maintain consistent and reliable orientation information at the network and ultimately the perceptual level.

Original languageEnglish (US)
Article number5
JournalJournal of Vision
Volume8
Issue number3
DOIs
StatePublished - Mar 10 2008

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Keywords

  • Aging
  • Contrast sensitivity
  • Masking
  • Orientation discrimination
  • Orientation tuning
  • Plasticity
  • Spatial vision

ASJC Scopus subject areas

  • Ophthalmology

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