Spatial summation in young and elderly observers

Brown, Brian; Peterken, Carolyn; Bowman, Kenneth J.; Crassini, Boris

doi:10.1111/j.1475-1313.1989.tb00913.x

Cited by 13 publications

(10 citation statements)

References 11 publications

(8 reference statements)

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“…A majority of research has reported that aging does not alter the summation area [5,19,22,24]. Given that previous research has demonstrated that age has little effect on sensitivity to low spatial frequencies [13,27,51] and sensitivity improves when the target is temporally modulated [30,49] as it was in our case, makes our findings consistent with this literature.…”

Section: Clinical Spatial Summationsupporting

confidence: 93%

Disclosing disease mechanisms with a spatio-temporal summation paradigm

Zele

O’Loughlin

Guymer

et al. 2005

Graefe's Arch Clin Exp Ophthalmo

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Section: Clinical Spatial Summationsupporting

confidence: 93%

Disclosing disease mechanisms with a spatio-temporal summation paradigm

Zele

O’Loughlin

Guymer

et al. 2005

Graefe's Arch Clin Exp Ophthalmo

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“…The average contrast energy values obtained (and 95% confidence intervals) were 17.94 (16.01, 19.94) for the younger observers and 24.34 (21.29, 27.47) for the older observers. As expected from previous investigations (Brown, Peierken, Bowman, & Crassini, 1989; Latham, Whitaker, & Wild, 1994; Werner et al, 2000), photopic increment thresholds are significantly elevated in older observers for foveal stimuli, but there is no significant change in spatial summation area with age.…”

Section: Resultssupporting

confidence: 87%

Senescent changes in photopic spatial summation

et al. 2011

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Previous studies have demonstrated an inverse relation between the size of the complete spatial summation area and ganglion cell density. We hypothesized that if this relation is dynamic, the spatial summation area at 6° nasal would expand to compensate for age-related losses of retinal ganglion cells but not in the fovea where age-related loss in ganglion cell density is not significant. This hypothesis was tested by measuring contrast thresholds with a series of Gabor patches varying in size. The spatial summation area was defined by the intersection of the segments of a two-branched, piece-wise linear function fitted to the data with slopes of −0.5 and 0 on a plot of log threshold vs. log area. Results demonstrate a 31% increase in the parafoveal spatial summation area in older observers with no significant age-related change in the fovea. The average foveal data show a significant increase in thresholds with age. Contrary to the foveal data, age comparisons of the parafoveal peak contrast thresholds display no significant difference above the summation area. Nevertheless, as expected from the increase in summation area, expressing the parafoveal thresholds as contrast energy reveals a significant difference for stimuli that are smaller than the maximal summation area.

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“…Larger, rather than smaller, summation areas for older compared to younger participants have been reported for static targets under scotopic viewing conditions (e.g., Schefrin et al, 1998). However, the majority of studies that have compared spatial summation for achromatic and chromatic static targets in young and old participants have, in the main, found no age-related differences in Ricco’s area (Dannheim and Drance, 1971; Brown et al, 1989; Redmond et al, 2010). This also appears to be the case for temporally-modulated targets (Zele et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

The ups and downs of global motion perception: a paradoxical advantage for smaller stimuli in the aging visual system

Hutchinson¹,

Ledgeway²,

Allen³

2014

Front. Aging Neurosci.

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Recent evidence suggests that normal aging is typically accompanied by impairment in the ability to perceive the global (overall) motion of visual objects in the world. The purpose of this study was to examine the interplay between age-related changes in the ability to perceive translational global motion (up vs. down) and important factors such as the spatial extent (size) over which movement occurs and how cluttered the moving elements are (density). We used random dot kinematograms (RDKs) and measured motion coherence thresholds (% signal elements required to reliably discriminate global direction) for young and older adults. We did so as a function of the number and density of local signal elements, and the aperture area in which they were displayed. We found that older adults’ performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display. In young adults, performance was also insensitive to element number and density but was modulated markedly by display size, such that motion coherence thresholds decreased as aperture area increased (participants required fewer local elements to move coherently to determine the overall image direction). With the smallest apertures tested, young participants’ motion coherence thresholds were considerably higher (~1.5 times worse) than those of their older counterparts. Therefore, when RDK size is relatively small, older participants were actually better than young participants at processing global motion. These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous. The results have important implications for the understanding of the consequences of aging on visual function and a number of potential explanations are explored. These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.

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Spatial summation in young and elderly observers

Cited by 13 publications

References 11 publications

Disclosing disease mechanisms with a spatio-temporal summation paradigm

Disclosing disease mechanisms with a spatio-temporal summation paradigm

Senescent changes in photopic spatial summation

The ups and downs of global motion perception: a paradoxical advantage for smaller stimuli in the aging visual system

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