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Neural bases of visual deficits during aging
1Department of Psychology, University of Wisconsin-Madison 53706.
Vision Research
|December 1, 1993
Summary
Visual abilities decline with age, but the neural causes remain unclear. Research suggests changes occur between the retina and visual cortex, though specific locations and mechanisms require further investigation.
Area of Science:
- Neuroscience
- Vision Science
- Gerontology
Background:
- Normal aging leads to declines in various visual abilities, including acuity, contrast sensitivity, and motion perception.
- These declines are not fully explained by optical changes, suggesting neural origins in the retina or central visual pathways.
Purpose of the Study:
- To investigate the neural bases of age-related visual deficits.
- To identify the specific locations and nature of neural changes contributing to vision loss in aging.
Main Methods:
- Review of psychophysical, anatomical, and physiological studies in humans and monkeys.
- Comparison of visual deficits with neurophysiological data and lesion-behavior studies.
- Analysis of retinal pattern-evoked electroretinograms (ERG) and cortical evoked potentials.
Main Results:
- Despite documented psychophysical declines, anatomical studies show minimal aging effects on the retino-geniculo-striate pathway.
- Retinal cell losses (rods, ganglion cells) are limited and show variability.
- Functional properties of neurons in the lateral geniculate nucleus (LGN) appear unaffected by aging in monkeys.
Conclusions:
- Neural changes contributing to age-related vision loss occur between the retina and striate cortex, but their exact location and nature are unknown.
- Current neurobiological methods are limited, and research needs better guidance from psychophysical data and examination of appropriate visual system locations.
- Large individual variability in aging effects complicates the detection of neural changes in small study samples.