Please use this identifier to cite or link to this item: http://repositorio.ufpa.br/jspui/handle/2011/5428
metadata.dc.type: Artigo de Periódico
Issue Date: Feb-2013
metadata.dc.creator: BARBONI, Mirella Telles Salgueiro
GOMES, Bruno Duarte
SOUZA, Givago da Silva
RODRIGUES, Anderson Raiol
VENTURA, Dora Selma Fix
SILVEIRA, Luiz Carlos de Lima
Title: Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics
Citation: BARBONI, M.T.S. et al. Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics. Brazilian Journal of Medical and Biological Research, Ribeirão Preto, v. 46, n. 2, p. 154-163, fev. 2013. Disponível em: <http://www.scielo.br/pdf/bjmbr/v46n2/bjb2428.pdf>. Acesso em: 12 fev. 2014. <http://dx.doi.org/10.1590/1414-431X20122428>.
Abstract: The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P < 0.05, ANOVA). Blue-yellow chromatic functions showed no specific tuning shape; however, at high spatial frequencies the evoked potentials showed higher contrast sensitivity than the psychophysical methods (P < 0.05, ANOVA). Evoked potentials can be used reliably to evaluate chromatic red-green CSFs in agreement with psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.
Keywords: Sensibilidade ao contraste
Visão de cores
Visão espacial
Psicofísica visual
Testes de avaliação da visão de cores
Limiares visual
ISSN: 1414-431X
metadata.dc.rights: Acesso Aberto
Appears in Collections:Artigos Científicos - NMT

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