Aging effects on contrast sensitivity in visual pathways: A pilot study on flicker adaptation

Abstract

Contrast sensitivity is reduced in older adults and is often measured at an overall perceptual level. Recent human psychophysical studies have provided paradigms to measure contrast sensitivity independently in the magnocellular (MC) and parvocellular (PC) visual pathways and have reported desensitization in the MC pathway after flicker adaptation. The current study investigates the influence of aging on contrast sensitivity and on the desensitization effect in the two visual pathways. The steady- and pulsed-pedestal paradigms were used to measure contrast sensitivity under two adaptation conditions in 45 observers. In the non-flicker adaptation condition, observers adapted to a pedestal array of four 1°×1° squares presented with a steady luminance; in the flicker adaptation condition, observers adapted to a square-wave modulated luminance flicker of 7.5 Hz and 50% contrast. Results showed significant age-related contrast sensitivity reductions in the MC and PC pathways, with a significantly larger decrease of contrast sensitivity for individuals older than 50 years of age in the MC pathway but not in the PC pathway. These results are consistent with the hypothesis that sensitivity reduction observed at the overall perceptual level likely comes from both the MC and PC visual pathways, with a more dramatic reduction resulting from the MC pathway for adults >50 years of age. In addition, a similar desensitization effect from flicker adaptation was observed in the MC pathway for all ages, which suggests that aging may not affect the process of visual adaptation to rapid luminance flicker.

The effect of acupuncture at the Taiyang acupoint on visual function and EEG microstates in myopia

“…Low and medium contrast visual functions are equally important in daily life (such as driving at night, reading newspapers, and identifying object boundaries, etc.) ( Onal et al, 2008 ; Roark and Stringham, 2019 ; Zhuang et al, 2021 ); however, whether acupuncture can improve the CS of patients with myopia is still uncertain.…”

Perceptual constancy of pareidolias across paper and digital testing formats in neurodegenerative diseases

“…Reallocation of visual processing resources from perceptual to cognitive domains (working memory, executive function) is suggested to affect performance in such modalities 28 . We speculate device-related changes in contrast sensitivity, resolution and brightness may affect sensory inputs impacting visual processing pathways 29,30 . Secondly, with respect to the study design, sNPT was always performed after pNPT.…”

Contrast Sensitivity Is Impaired in Suspected Primary Open-Angle Glaucoma Patients

“…The effect of participants’ age in CS has been largely studied (Derefeldt et al, 1979; McKendrick et al, 2007; Santillán et al, 2014; Zhuang et al, 2021) demonstrating that older adults have lower CS than younger ones, caused by age changes of optical and neural factors. Indeed, a marked CS difference in healthy individuals was established between groups under and over 50 years of age (Santillán et al, 2014; Zhuang et al, 2021). For this reason, it is essential to differentiate age ranges when comparing patients with healthy individuals.…”