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David Chan, Liza igochine, Lynn Hasher, Jay Pratt; Turn up the noise: Increased visual noise in the M-pathway in older adults. Journal of Vision 2016;16(12):784. doi: 10.1167/16.12.784.
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© ARVO (1962-2015); The Authors (2016-present)
Visual information in humans is processed by two separate visual pathways. One is the magnocellular visual pathway (M-pathway), which carries high temporal frequency information but low spatial frequency information. The other is the parvocellular visual pathway (P-pathway), which carries low temporal information but high spatial information. Currently, very little is known about how these pathways may change with age. In order to investigate this issue, we presented older and younger adults with low and high spatial frequency gabors under two critical conditions. The first, a pulsed pedestal condition, is known to inhibit the M-pathway, while the second, a steady pedestal condition, leaves both the M and the P-pathways intact. With younger adults, as expected, we found that they are faster at processing low spatial frequency (LSF) information under the steady pedestal condition, in which the M-pathway is unaffected. This replicates previous findings with younger adults. Also as expected, this bias is removed under the pulsed pedestal condition, where no preferential processing is shown between low and high spatial frequency information. These findings replicate earlier work (e.g., (e.g., Abrams & Weidler, 2014; Goodhew et al., 2014). Regarding older adults, we demonstrate the same pattern in the steady pedestal condition; faster processing of LSF information. Interestingly, an even greater inhibition towards LSF information is produced under the pulsed pedestal condition, such that now speeded processing occurs towards HSF information. We argue that this difference in older adults provides evidence that the M-pathway, although very much intact, may contain more internal noise, manifesting itself in a greater inhibition of low spatial frequency processing when the M-pathway is repressed.
Meeting abstract presented at VSS 2016
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