Variaçao circadiana da sensibilidade visual acromática e cromática

• Autor(a) principal: Andrade, Michael Jackson Oliveira de
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/11613
• topic: Ritmo circadiano; Cronotipo; Psicofísica visual; Sensibilidade ao contraste; Cor; Circadian rhythm; Chronotype; Visual psychophysics; Contrast sensitivity; Color; CNPQ::CIENCIAS HUMANAS::PSICOLOGIA

The detection of the visual threshold has a fluctuating pattern over the hours of the day. Studies has been demonstrating the existence of a circadian rhythm in the human visual sensitivity. Thus, this study aimed to measure the visual contrast sensitivity achromatic and the color discrimination during a circadian rhythm. The study included 28 young adult male. The subjects were divided into three groups according to the chronotype: Moderate Matutinal (n = 8, M = 23.25, SD = 2.6); Indifferent (n = 10, M = 23.30, SD = 2.7) and moderately Evening (n = 10, M = 23.70, SD = 2.5). Among the tools to assess the patterns of sleep behavioral were used the Pittsburgh Sleep Quality Index, the sleep diary and MorningnessEveningness self-assessment questionnaire of Horne and Ostberg. It was used the Metropsis software version 11.0 of Cambridge Research Systems to measure the visual contrast sensitivity (VCS) and the Cambridge Colour Test software to check the discrimination of colors on the axes of confusion protan, deutan and tritan. It was also used the desaturated Panel D-15 Lanthony. The VCS was measured from vertical sinusoidal grating patterns with spatial frequencies of 0.2; 0.6; 1; 3.1; 6.1; 8.8, 13.2 and 15.6 cpd. The stimuli were presented on a CRT color display with flat screen 19 inch monitor, resolution of 1,024 x 786 pixels and 100 Hz refresh rate. The monitor is controlled by a microcomputer via a video card with VGA input and DVI, connected to the visage. The luminance and gamma correction were adjusted to LightScan program and the optical photometer. All measurements were performed on condition of photopic luminance (39.6 cd/m²). The results showed that the subjects differ in the wake up behavior on weekdays (p< 0.05) and weekend (p<0.05). The subjects moderately vespertine wake up 2h later than the subjects moderately matutinal (p<0.05). The MANOVA showed drowsiness among subjects in both days of the week (p<0.05) and the weekend (p<0.05), especially at 9am (p<0.05) and 21h (p< 0,05).In general, the subjects presented curves sensitivity visual contrast with peak in the spatial frequency of 3.1 cpd. The MANOVA showed difference between the horary and groups in spatial frequencies of 0.2 (? = 0.49; F(8,40) = 2.37, p<0.05; ?² = 0.76); 0.6 (? = 0.14; F(8,40) = 9.42, p<0.05; ?² = 0.63); 3.1 (? = 0.31; F(8,40) = 4.37, p<0.05; ?² = 0.44) and 8.8 (? = 0.12, F(8,40) = 10.31; p<0.05; ?² = 0.65). The results show higher contrast sensitivity for subjects with chronotype moderately vespertine both at 9am 17h and 21h in spatial frequencies low, medium and high. The sensitivity indicator for group moderately vespertine was confirmed by the sensitivity of the areas of ellipses deutan (? = 0.36; F(8,34) = 1.99, p<0.05; ?² = 0.40) and tritan (? = 0.44; F(8,40) = 2.55, p<0.05; ?² = 0.34), especially in times of 9am and 21pm. The subjects moderately vespertine are more sensitive to achromatic and chromatic contrast, regardless of the hour of measurement. The results show that the mechanisms related to the entrainment of the circadian informations that processes color have intrinsically parallel functions to the mechanisms that render shine. The differences between the groups may be related to the mechanisms or visual pathways that filter spatial information in accordance with variations linked to the pattern of chronotype, the length of visual wave and hour of exposure to light of the subjects.