Michael Jackson Oliveira de Andrade

Colour discrimination thresholds in type 1 Bipolar Disorder: a pilot study

Although some studies have reported perceptual changes in psychosis, no definitive conclusions have been drawn about visual disturbances that are related to bipolar disorder (BPD). The purpose of the present study was to evaluate colour vision in BPD patients. Data were recorded from 24 participants: healthy control group (n = 12) and type 1 BPD group (n = 12). The participants were 20–45 years old and they were free from neurological disorders and identifiable ocular disease and had normal or corrected-to-normal visual acuity. Colour discrimination was evaluated using the Lanthony D-15d, Trivector and Ellipse tests, using a psychophysical forced-choice method. The relationship of visual measures to mood state and cognitive function was also investigated. The results showed that BPD patients had higher colour discrimination thresholds in the D15d (p < 0.001), Trivector (p < 0.001) and Ellipse (p < 0.01) tests compared with healthy controls. Linear regression analysis showed that mood state was related to colour discrimination. BPD individuals were not impaired in cognitive tasks. The present study provided new evidence of potential links between type 1 BPD and visual processing impairments. This research suggests a new direction for studies and the need for research in this field of study.

Influência do Cronotipo e do Horário da Medida na Sensibilidade ao Contraste Visual

This study aimed to evaluate the contrast sensitivity curve for the stimuli of vertical sinusoidal grids with spatial frequencies of .2; .6; 1; 3.1; 6.1; 8.8; 13.2 and 15.6 cycles per degree of visual angle, in a 24- hour rhythm of healthy adults of different chronotypes. This study had 18 participants aged 19 to 31 years (M=23.8; SD=3.29) divided into groups according to the chronotype: Morningness (n=5), Intermediate (n=9) and Moderate Eveningness (n=4). Neuropsychological measures and the Metropsis software were used to evaluate the Contrast Sensitivity Function (CSF). CSF measurements were performed by the psychophysical method of forced choice between two spatial alternatives. Results showed significant changes in the dimensions related to cognitive processing and CSF for morning subjects [F (14; 76303) = 38.92; p < .05], Intermediate subjects [F (14, 505) = 2.79; p< .05] and moderately evening subjects [F (14, 279) = 2.75; p< .05] in accordance with the measured time. The study concluded that contrast sensitivity is an important aspect to the study of circadian visual perception, suggesting that the sensorial mechanisms which process visual contrast are directly related to the time and pattern of peoples chronotypes.

Tobacco Use Decreases Visual Sensitivity in Schizophrenia

Smoking prevalence in patients who are diagnosed with schizophrenia (SCZ) is higher than in the general population. Chronic tobacco use in SCZ patients may reduce the side effects of antipsychotic drugs, thus serving as a self-medication for such side effects. Understanding the ways in which chronic tobacco use influences visual sensitivity has clinical implications, which may serve as a tool for non-invasively diagnosing early-stage visual processing deficits. The present study evaluated the effects of chronic tobacco use on visual sensitivity in SCZ patients. Our purpose was to provide new directions for future research, mainly psychophysical and electrophysiological studies. In the present study, 40 smoker controls (SC), 20 SCZ tobacco users, and 20 SCZ tobacco nonusers were recruited from the Psychosocial Care Center. Visual sensitivity was compared between both SCZ groups and the SC group. Patients with SCZ who were chronic tobacco users presented lower visual sensitivity for chromatic (p < 0.001) and achromatic (p < 0.001) stimuli compared with the other groups. Our findings highlight the need to evaluate possible addictive behavior in patients with SCZ, which may contribute to public policies that seek to improve the quality of life of SCZ patients and their families.

Daily variation of visual perception of colors: Preliminary studies.

This study aimed to measure the axes of colors confusion according to the circadian typology (CT). For this purpose, 28 young male adults aged 20 to 28 participated in this study. The characteristics of the sample were: morning moderately (MM; n = 8; M = 23.25 ± 2.6); Intermediate (I; n = 10; M = 23.30 ± 2.7) and evening moderately (EM; n = 10; M = 23.70 ± 2.5). We used the Pittsburgh Sleep Quality Index (PSQI) and Horne and Ostberg’s questionnaire to ascertain aspects of sleep quality and CT and Cambridge Colour Test (CCT) and the Lanthony Desaturated D-15 Test (D-15d) to verify the color perception. Significant difference was found in the PSQI (F(2.20) = 15.77, p < .001; &eegr;2 = 0.62) between EM compared with I (p < .001) and MM (p < .001). We found a difference in the protan confusion axes at 9 a.m. (&khgr;2 = 6.74; p < .05) and 9 p.m. (&khgr;2 = 7.11; p < .05) and deutan at 5 p.m. (&khgr;2 = 11.23, p < .001). The chromatic confusion axes will vary according to the synchronization of daily variation and the EM typology has higher chromatic sensitivity, pointing to a possible relation between visual circadian filters and spatial chromatic information. The daily fluctuation of visual sensitivity may explain the preliminary results on the circadian effects on color perception.

Daily variation of visual sensitivity to luminance contrast: Effects of time of measurement and circadian typology

ABSTRACT This study analyzed the fluctuation of the achromatic visual contrast sensitivity (CS) of adult males (M = 23.42 ± 2.6 years) during a daily period. Twenty-eight volunteers were divided into three groups according to circadian typology (CT): moderate morning (MM; n = 8); intermediate (I; n = 10) and moderate evening (ME; n = 10). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and the Horne and Ostberg Morningness-Eveningness Questionnaire was used to measure CT. To measure CS, we used Metropsis software version 11.0 with vertical sinusoidal grids of 0.2, 0.6, 1, 3.1, 6.1, 8.8, 13.2 and 15.6 cycles per degree of visual angle (cpd). The stimuli were presented on a cathode ray tube (CRT) color video monitor with a 19-inch flat screen, a 1024 × 786 pixel resolution, a 100 Hz refresh rate and a photopic luminance of 39.6 cd/m2. It was inferred that there is a tendency for visual contrast to vary according to daily rhythmicity and CT, mainly for the median spatial frequencies (1.0 cpd, χ2 = 9.93, p < 0.05 and 3.1 cpd, χ2 = 10.33, p < 0.05) and high spatial frequencies (13.2 cpd, χ2 = 11.54, p < 0.05) of ME participants. ME participants had minimal visual contrast sensitivity during the morning shift and a progressive increase from afternoon to night.

Chronic occupational exposure to low levels of organic vapors can affect color vision and contrast sensitivity.

This study evaluated the level of exposure to organic vapors in chromatic and achromatic vision of 38 male gas-station workers (average of 6.82 ± 5.62 years worked). The level of exposure was found by passive method with gas chromatography. Color vision was assessed by Lanthony desaturated D15 tests (D15d; Lanthony, 1978) the Cambridge Color Test (CCT; Mollon, & Reffin, 1989), and contrast sensitivity by sinusoidal gratings at frequencies 0.2, 0.5, 1, 2.0, 5, 10 and 16 cycles per degree (cpd). The highest average daily concentrations found in gasoline (168 ppm) were below the threshold limit values (300 ppm), yet gas-station workers had a higher color-confusion index (CCI) for D15d (p < .01), predominantly for blue/yellow (75%), larger ellipse areas in the CCT (p < .05), and lower sensitivity contrast for 5, 10, and 16 cpd (p < .01). Prolonged service time correlated with the areas A1 (&rgr; = 0.46; p < .01), A2 (&rgr; = 0.63; p < .01), and 5 cpd (&rgr; = – 0.36; p < .05). Gas-station attendants with 8–20 years of service had lower performances for the areas A1 and A2 (p < .0083) than those with less exposure (1–3 years of service). The results show that chronic exposure to organic vapors can reduce the chromatic and achromatic visual perception of luminance in gas-station workers with age, even at low levels, suggesting the inadequacy of tolerance levels used for gasoline. The also highlight the need for chronic systematic long-term monitoring, and not just daily.

Chronic Organic Solvent Exposure Changes Visual Tracking in Men and Women

Organic solvents can change CNS sensory and motor function. Eye-movement analyses can be important tools when investigating the neurotoxic changes that result from chronic organic solvent exposure. The current research measured the eye-movement patterns of men and women with and without histories of chronic organic solvent exposure. A total of 44 volunteers between 18 and 41 years old participated in this study; 22 were men (11 exposed and 11 controls), and 22 were women (11 exposed and 11 controls). Eye movement was evaluated using a 250-Hz High-Speed Video Eye Tracker Toolbox (Cambridge Research Systems) via an image of a maze. Specific body indices of exposed and non-exposed men and women were measured with an Inbody 720 to determine whether the differences in eye-movement patterns were associated with body composition. The data were analyzed using IBM SPSS Statistics version 20.0.0. The results indicated that exposed adults showed significantly more fixations (t = 3.82; p = 0.001; r = 0.51) and longer fixations (t = 4.27; p = 0.001, r = 0.54) than their non-exposed counterparts. Comparisons within men (e.g., exposed and non-exposed) showed significant differences in the number of fixations (t = 2.21; p = 0.04; r = 0.20) and duration of fixations (t = 3.29; p = 0.001; r = 0.35). The same was true for exposed vs. non-exposed women, who showed significant differences in the number of fixations (t = 3.10; p = 0.001; r = 0.32) and fixation durations (t = 2.76; p = 0.01; r = 0.28). However, the results did not show significant differences between exposed women and men in the number and duration of fixations. No correlations were found between eye-movement pattern and body composition measures (p > 0.05). These results suggest that chronic organic solvent exposure affects eye movements, regardless of sex and body composition, and that eye tracking contributes to the investigation of the visual information processing disorders acquired by workers exposed to organic solvents.

Haptic memory and forgetting: a systematic review

Memory is a multiple system composed of encoding, storage and retrieval of information subsystems. The memory tactile, haptic memory submodality is connected to haptic perception; it concerns the active manipulation of objects. This study is a systematic review related to forgetting occurred in haptic memory. Articles was sought in electronic databases PsycINFO, PubMed, and Web of Science, using the keywords “haptic memory”, “touch memory”, “tactile memory”, “tactual memory” separately, and then combined with the word “forgetting”. These words were identified in 1655 publications. But lastly, six articles published between 2002 and 2012 were selected by a set of inclusion criteria. Largely referred to studies that used behavioral methods recognition procedures, and using real objects. However, the types of memory test used and the number of objects and the time interval between sessions of study and test had great variation.