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Title: Psychophysical analysis of contrast processing segregated into magnocellular and parvocellular systems in asymptomatic carriers of 11778 Leber's hereditary optic neuropathy
Authors: Gualtieri, Mirella
Bandeira, M.
Hamer, R. D.
Costa, Marcelo Fernandes
Oliveira, André G. Fernandes
Moura, A. L. A.
Sadun, Federico
De Negri, Anna Maria
Berezovsky, Adriana [UNIFESP]
Salomão, Solange Rios [UNIFESP]
Carelli, Valerio
Sadun, Alfredo Arrigo
Ventura, Dora Fix
Universidade de São Paulo (USP)
Osped S Giovanni Evangelista
Azienda Osped S Camillo Forlanini
Universidade Federal de São Paulo (UNIFESP)
Univ Bologna
Univ So Calif
Smith Kettlewell Eye Res Inst
Keywords: Leber's hereditary optic neuropathy
contrast sensitivity
temporal integration
Issue Date: 1-May-2008
Publisher: Cambridge Univ Press
Citation: Visual Neuroscience. New York: Cambridge Univ Press, v. 25, n. 3, p. 469-474, 2008.
Abstract: We examined achromatic contrast discrimination in asymptomatic carriers of 11778 Leber's hereditary optic neuropathy (LHON 18 controls) and 18 age-match were also tested. To evaluate magnocellular (MC) and Parvocellular (PC) contrast discrimination, we used a version of Pokorny and Smith's (1997) Pulsed/steady-pedestal paradigms (PPP/SPP) thought to be detected via PC and MC pathways, respectively. A luminance pedestal (four 1 degrees x 1 degrees squares) was presented on a 12 cd/m(2) surround. the luminance of one of the squares (trial square, TS) was randomly incremented for either 17 or 133 ms. Observers had to detect the TS, in a forced-choice task, at each duration, for three pedestal levels: 7, 12, 19 cd/m(2). in the SPP, the pedestal was fixed, and the TS was modulated. for the PPP, all four pedestal squares pulsed for 17 or 133 ms, and the TS was simultaneously incremented or decremented. We found that contrast discrimination thresholds of LHON carriers were significantly higher than controls' in the condition with the highest luminance of both paradigms, implying impaired contrast processing with no evidence of differential sensitivity losses between the two systems. Carriers' thresholds manifested significantly longer temporal integration than controls in the SPP, consistent with slowed MC responses. the SPP and PPP paradigms can identify contrast and temporal processing deficits in asymptomatic LHON carriers, and thus provide an additional tool for early detection and characterization of the disease.
ISSN: 0952-5238
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