Luminance affects age-related deficits in object detection: implications for computerized psychological assessments

Effect of visual cues on the resolution of perceptual ambiguity in Parkinson's disease and normal aging

Parkinson's disease (PD) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. This raises the question of the extent to which these groups use visual cues when disambiguating information. Twenty-seven individuals with PD, 23 normal control adults (NC), and 20 younger adults (YA) were presented a Necker cube in which one face was highlighted by thickening the lines defining the face. The hypothesis was that the visual cues would help PD and NC to exert better control over bistable perception. There were three conditions, including passive viewing and two volitional-control conditions (hold one percept in front; and switch: speed up the alternation between the two). In the Hold condition, the cue was either consistent or inconsistent with task instructions. Mean dominance durations (time spent on each percept) under passive viewing were comparable in PD and NC, and shorter in YA. PD and YA increased dominance durations in the Hold cue-consistent condition relative to NC, meaning that appropriate cues helped PD but not NC hold one perceptual interpretation. By contrast, in the Switch condition, NC and YA decreased dominance durations relative to PD, meaning that the use of cues helped NC but not PD in expediting the switch between percepts. Provision of low-level cues has effects on volitional control in PD that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity.

At the interface of sensory and motor dysfunctions and Alzheimer's disease

Recent evidence indicates that sensory and motor changes may precede the cognitive symptoms of Alzheimer's disease (AD) by several years and may signify increased risk of developing AD. Traditionally, sensory and motor dysfunctions in aging and AD have been studied separately. To ascertain the evidence supporting the relationship between age-related changes in sensory and motor systems and the development of AD and to facilitate communication between several disciplines, the National Institute on Aging held an exploratory workshop titled "Sensory and Motor Dysfunctions in Aging and AD." The scientific sessions of the workshop focused on age-related and neuropathologic changes in the olfactory, visual, auditory, and motor systems, followed by extensive discussion and hypothesis generation related to the possible links among sensory, cognitive, and motor domains in aging and AD. Based on the data presented and discussed at this workshop, it is clear that sensory and motor regions of the central nervous system are affected by AD pathology and that interventions targeting amelioration of sensory-motor deficits in AD may enhance patient function as AD progresses.

Vision-fair neuropsychological assessment in normal aging, Parkinson's disease and Alzheimer's disease

We examined performance of healthy older and younger adults and individuals with Alzheimer's disease (AD) and Parkinson's disease (PD) on digit cancellation, a task putatively sensitive to cognitive impairment, but possibly affected by visual impairment, particularly in contrast sensitivity. Critical contrast thresholds were established to create custom stimulus arrays that were proximally matched across individuals. Age- and PD-related differences in search were fully accounted for by the sensory deficit. Increased contrast benefited AD patients, but could not override cognitive impairment. We conclude that visually fair neuropsychological testing can effectively compensate for normal age- and PD-related visual changes that affect cognitive performance.

Aging and vision: changes in function and performance from optics to perception

Age-related declines in vision can have a major impact on the health and well-being of an older population. A review of research on aging and vision indicates that these declines occur at multiple levels of the visual system including optics, sensory processing, and perceptual processing and are not likely due to a systemic change in brain function (e.g., generalized slowing; common cause hypothesis) as a result of normal aging. In addition, declines in sensory and perceptual processing are not due to low-level explanations such as the amount of light that reaches the retina. Declines in visual performance are due to a variety of distinct factors that include spatial integration and difficulty in processing visual information in the presence of noise. Neurophysiological studies suggest that processing declines may be due in part to changes in cortical inhibition mediated by changes in the level of neurotransmitters associated with inhibition. Despite the widespread declines in function with normal aging, recent research suggests that perceptual learning can be used to dramatically improve visual function for older individuals. This research suggests a high degree of plasticity of the visual system among older populations and suggests that perceptual learning is an important tool for the recovery of age-related declines in vision. WIREs Cogn Sci 2012, 3:403-410. doi: 10.1002/wcs.1167 For further resources related to this article, please visit the WIREs website.