title: Differential effects of alcohol on contrast processing mediated by the magnocellular and parvocellular pathways.
abstract: This study investigated how acute alcohol intake affects contrast processing mediated by inferred magnocellular (MC) and parvocellular (PC) pathways. Achromatic contrast discrimination thresholds were measured in 16 young healthy participants using a steady-pedestal, pulsed-pedestal or pedestal-Δ-pedestal paradigm designed to favor the inferred MC or the PC pathway. Each participant completed two randomized sessions that included consumption of either 0.8 g/kg alcohol or a placebo beverage, with each session consisting of contrast discrimination measurements at baseline and at 60 min following beverage consumption. The results showed that, compared to placebo, alcohol significantly reduced MC contrast sensitivity and PC contrast gain but had no effect on PC contrast sensitivity for the majority of the participants; and did not alter MC contrast gain consistently across participants. The decrease in contrast gain in the PC pathway can be interpreted as a degradation of the postretinal signal-to-noise ratio, whereas the decrease of sensitivity in the MC pathway likely results from a change of cortical processing.
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA. xzhuang@uic.edu
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhuang
authors.forename: Andrea
authors.initials: A
authors.lastname: King
authors.forename: Patrick
authors.initials: P
authors.lastname: McNamara
authors.forename: Joel
authors.initials: J
authors.lastname: Pokorny
authors.forename: Dingcai
authors.initials: D
authors.lastname: Cao
mesh_terms: D000328:Adult; D002492:Central Nervous System Depressants / Q000494:pharmacology; D003117:Color Vision Defects / Q000139:chemically induced* / Q000503:physiopathology; D015350:Contrast Sensitivity / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics / Q000379:methods; D012016:Reference Values; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology*
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol