Impulse response of an S-cone pathway in the aging visual system

Keizo Shinomori, John S Werner

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Abstract

Age-related changes in the temporal properties of an S-cone pathway were characterized by the psychophysical impulse-response function (IRF). Participants included 49 color-normal observers ranging in age from 16.8 to 86.3 years. A double-pulse method was used to measure the IRF with S-cone modulation at constant luminance. Stimuli were presented as a Gaussian patch (±1SD=2.3°) in one of four quadrants around a central fixation cross on a CRT screen. The test stimulus was modulated from the equal-energy white of the background toward the short-wave spectrum locus. Each of the two pulses (6.67 ms) was separated by an interstimulus interval (ISI) from 20 to 720 ms. Chromatic detection thresholds were determined by a four-alternative forced-choice method with staircases for each ISI in one session. IRFs were calculated from the threshold data using a model with four parameters of an exponentially damped sine wave. S-cone IRFs have only an excitatory phase and a much longer time course compared with IRFs for luminance modulation measured with the same apparatus. The results demonstrated significant age-related losses in IRF amplitude, but the latency (time to peak) of the IRF was stable with age.

Original languageEnglish (US)
Pages (from-to)1570-1577
Number of pages8
JournalJournal of the Optical Society of America A: Optics and Image Science, and Vision
Volume23
Issue number7
DOIs
StatePublished - 2006

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Computer Vision and Pattern Recognition

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