Home Itens selecionados Provedores de dados OAI Créditos Sobre Ajuda

			Busca avançada
	Provedor de dados BJMBR (3) Autor Gomes,B.D. (2) Silveira,L.C.L. (2) Souza,G.S. (2) Ventura,D.F. (2) Barboni,M.T.S. (1) Costa,T.L. (1) Fitzgerald,M.E.C. (1) Moura,A.L.A. (1) Nogueira,R.M.T.B.L. (1) Pereira,A.G.F. (1) Rodrigues,A.R. (1) Santos,N.A. (1) Schakelford,H.B. (1) Mais... Palavra-chave Spatial vision (3) Contrast sensitivity (2) Aging (1) Circular gratings (1) Color vision (1) Contrast vision (1) Linear gratings (1) Multifocal visual evoked cortical potential (1) Psychophysics (1) Signal-to-noise analysis (1) Steady-state visual evoked cortical potential (1) Visual electrophysiology (1) Visual thresholds (1) Mais... Tipo do documento Info:eu-repo/semantics/article (3) Ano 2013 (2) 2012 (1) País Brazil (3) Idioma Inglês (3)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 3 Primeira ... 1 ... Última Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics BJMBR Barboni,M.T.S.; Gomes,B.D.; Souza,G.S.; Rodrigues,A.R.; Ventura,D.F.; Silveira,L.C.L.. 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... Tipo: Info:eu-repo/semantics/article Palavras-chave: Contrast sensitivity; Color vision; Steady-state visual evoked cortical potential; Visual thresholds; Spatial vision; Psychophysics. Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013000200154 Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings BJMBR Costa,T.L.; Nogueira,R.M.T.B.L.; Pereira,A.G.F.; Santos,N.A.. Changes in visual function beyond high-contrast acuity are known to take place during normal aging. We determined whether sensitivity to linear sine-wave gratings and to an elementary stimulus preferentially processed in extrastriate areas could be distinctively affected by aging. We measured spatial contrast sensitivity twice for concentric polar (Bessel) and vertical linear gratings of 0.6, 2.5, 5, and 20 cycles per degree (cpd) in two age groups (20-30 and 60-70 years). All participants were free of identifiable ocular disease and had normal or corrected-to-normal visual acuity. Participants were more sensitive to Cartesian than to polar gratings in all frequencies tested, and the younger adult group was more sensitive to all stimuli tested. Significant... Tipo: Info:eu-repo/semantics/article Palavras-chave: Contrast sensitivity; Circular gratings; Linear gratings; Aging; Spatial vision. Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013001000855 Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation BJMBR Souza,G.S.; Schakelford,H.B.; Moura,A.L.A.; Gomes,B.D.; Ventura,D.F.; Fitzgerald,M.E.C.; Silveira,L.C.L.. This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation... Tipo: Info:eu-repo/semantics/article Palavras-chave: Multifocal visual evoked cortical potential; Contrast vision; Spatial vision; Signal-to-noise analysis; Visual electrophysiology. Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012001000011 Registros recuperados: 3 Primeira ... 1 ... Última

Empresa Brasileira de Pesquisa Agropecuária - Embrapa Todos os direitos reservados, conforme Lei n° 9.610 Política de Privacidade Área restrita		Embrapa Parque Estação Biológica - PqEB s/n° Brasília, DF - Brasil - CEP 70770-901 Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco