Exposure to a high altitude hypoxia environment has significant negative effects on human central nervous system. Many previous studies have explored the influence of the high altitude environment on human color perception in a simulated high altitude environment or in an environment acutely exposed to high altitude, but little has been done in migrators and natives exposed to high altitude and low oxygen for a long period of time. In this study, the minimal-change method was used to examine whether the color perception of red, green, blue and yellow was affected by the high altitude in 30 plain residents, 30 Han migrators who have lived in the high altitude for 2 years, and 28 high-altitude-adapted Tibetan natives. The results showed that long-term high altitude exposure had the most significant effect on the blue and red color perception in the natives and the migrators, with the effect on the blue color being significantly greater than that on the red color. However, the effects on green color processing only happened to the natives. The results suggest that there is an internal correlation between blood supply and selectivity changes of visual color processing caused by exposure to the plateau environment.
Altitude ; China ; Color Perception ; physiology ; Humans ; Hypoxia ; Oxygen ; metabolism

OBJECTIVE: To investigate the changes of color pattern reversal visual evoked potential (CPR-VEP)of primary glaucoma using different temporal frequencies, and to search for the best temporal frequency parameters and color parameters. METHODS: Vision Monitor visual electrophysiograph (Métrovision, France) was used to record CPR-VEP at different temporal frequencies (1, 2, 4, 8, 16, and 32 Hz) and different color stimulations (black/white, red/green, blue/yellow) in 41 cases (70 eyes) with primary glaucoma (glaucoma group) and 13 normal subjects (26 eyes) (normal control group). P100 wave amplitudes were compared. RESULTS: (1) In the normal control group, P100 amplitudes declined while the temporal frequency of black/white stimulation was increasing, but they had peaks at 2 Hz and 8 Hz red/green stimulation and blue/yellow stimulation. (2) In the glaucoma group, CPR-VEP P100 declined while temporal frequency was increasing under 3 color stimulations, but had a peak at 8 Hz. At 2 Hz-16 Hz, P100 amplitudes were related with the mean defect of Humphrey visual field, especially with all 3 color stimulations at 8 Hz and with blue/yellow stimulation at 2 Hz and 16 Hz. (3) P100 amplitude was most different under the 3 color stimulations between the 2 groups at 8 Hz. CONCLUSION The changes of CPR-VEP P(100) amplitude can objectively reflect the glaucoma visual function damage. CPR-VEP P100 amplitude has certain value in studying glaucoma under different color stimulations (black/white, red/green, blue/yellow) at 8 Hz, and blue/yellow stimulation at 2 Hz and 16 Hz.
Adult ; Aged ; Color Perception ; physiology ; Color Perception Tests ; methods ; Evoked Potentials, Visual ; physiology ; Female ; Glaucoma ; diagnosis ; physiopathology ; Humans ; Male ; Middle Aged

Dynamic color is an important carrier that takes information in some special occupations. However, up to the present, there are no available and objective tests to evaluate dynamic color processing. To investigate the characteristics of dynamic color processing, we adopted two patterns of visual stimulus called "onset-offset" which reflected static color stimuli and "sustained moving" without abrupt mode which reflected dynamic color stimuli to evoke event-related brain potentials (ERPs) in primary color amblyopia patients (abnormal group) and subjects with normal color recognition ability (normal group). ERPs were recorded by Neuroscan system. The results showed that in the normal group, ERPs in response to the dynamic red stimulus showed frontal positive amplitudes with a latency of about 180 ms, a negative peak at about 240 ms and a peak latency of the late positive potential (LPP) in a time window between 290 and 580 ms. In the abnormal group, ERPs in response to the dynamic red stimulus were fully lost and characterized by vanished amplitudes between 0 and 800 ms. No significant difference was noted in ERPs in response to the dynamic green and blue stimulus between the two groups (P>0.05). ERPs of the two groups in response to the static red, green and blue stimulus were not much different, showing a transient negative peak at about 170 ms and a peak latency of LPP in a time window between 350 and 650 ms. Our results first revealed that some subjects who were not identified as color blindness under static color recognition could not completely apperceive a sort of dynamic red stimulus by ERPs, which was called "dynamic red blindness". Furthermore, these results also indicated that low-frequency ERPs induced by "sustained moving" may be a good and new method to test dynamic color perception competence.
Adult ; Color Perception ; physiology ; Color Vision Defects ; diagnosis ; physiopathology ; Event-Related Potentials, P300 ; physiology ; Evoked Potentials, Visual ; physiology ; Female ; Humans ; Male ; Pattern Recognition, Visual ; physiology ; Young Adult

The cone cell on the retina of human is the sensor of vision under illumination; it can be classified into three types: red cone cell, green cone cell, and blue cone cell. There is different property of absorbing light for each type of cone cell. In this work, a 10 Hz pulse was used to drive red, green and blue light emitting diodes respectively, and the different monochromatic light with the same luminance was obtained. The eyes of ten subjects were stimulated by different monochromatic light independently; an EGI system with 128 channels was used to record the steady-state visually evoked potential (SSVEP). After applying the fast fourier transform (FFT) to the SSVEP data, we found that the distribution of the neural network in the initial vision cortex activated by the output of the different-typed cone cell remained mainly identical, but there was some difference in intensity between the three types of network: the activity by blue light is the strongest one, that by red light is in the middle, and that by green light is the weakest one.
Brain ; physiology ; Color ; Color Perception ; physiology ; Electroencephalography ; methods ; Evoked Potentials, Visual ; physiology ; Female ; Humans ; Light ; Male ; Photic Stimulation ; Retinal Cone Photoreceptor Cells ; physiology ; Young Adult

The VEPs evoked by different colors are differently distributed on human cerebral cortex. This study sought to shed light on the spatio-temporal distribution of chromatic VEPs and compare the distribution characteristics of chromatic VEPs evoked by different colors in different cerebral cortex regions. The subjects were asked to stare at the red, green, black gradient bars against a white background. The results show that the latency periods and the amplitudes of P1 and N1 peaks from different chromatic VEPs exhibit significant differences (P<0.001). The speed and intensity of cognitive task of red are higher than those of green. The latency periods and the amplitudes of P1 and N1 peaks from different cerebral cortex regions also display remarkable differences (P<0.001). The intensity of reaction in the temporal and occipital regions is stronger than that in other regions, and the latency periods in frontal area and central area are shorter than those in temporal and occipital regions.
Adult ; Cerebral Cortex ; physiology ; Color ; Color Perception ; physiology ; Electroencephalography ; Evoked Potentials, Visual ; physiology ; Female ; Humans ; Male ; Signal Processing, Computer-Assisted ; Young Adult

PURPOSE: Our objective was to estimate the maximum color contrast sensitivity (MCCS) thresholds in individuals with chiasma opticum damage. METHODS: The pilot study tested 41 people with pituitary adenoma (PA) and 100 age- and gender-matched controls. Patients were divided into two groups according to PA size, PA ≤1 cm or PA >1 cm. A new MCCS test program was used for color discrimination. RESULTS: The mean total error score (TES) of MCCS was 1.8 in the PA ≤1 cm group (standard deviation [SD], 0.38), 3.5 in the PA >1 cm group (SD, 0.96), and 1.4 in the control group (SD, 0.31; p < 0.001). There was a positive correlation between tumor size and MCCS result (r = 0.648, p < 0.01). In the group that had PA-producing hormones, the TES was 2.5 (SD, 1.09), compared to 4.2 value in the non-functioning PA group of patients that did not have clinically significant hormone excess (SD, 3.16; p < 0.01). In patients with normal visual acuity (VA) or visual field MCCS, the TES was 3.3 (SD, 1.8), while that in patients with VA <0.00 was 4.6 (SD, 2.9). CONCLUSIONS: Results of the MCCS test TES were 1.9 times better in patients with PA ≤1 cm compared to patients with PA >1 cm (p < 0.01). In PA patients with normal VA, the TES was 2.35 times worse than that of healthy persons (p < 0.01).
Adenoma/*complications/diagnosis ; Adolescent ; Adult ; Aged ; Color Perception/physiology ; Color Perception Tests/*methods ; Contrast Sensitivity/*physiology ; *Early Diagnosis ; Female ; Humans ; Male ; Middle Aged ; *Optic Chiasm ; Pilot Projects ; Pituitary Neoplasms/*complications/diagnosis ; Time Factors ; Vision Disorders/*diagnosis/etiology/physiopathology ; Visual Fields ; Young Adult

PURPOSE: To investigate patterns of functional magnetic resonance imaging (fMRI) activation during sentence reading before and after wearing color-tinted lenses. METHODS: A total of 15 Meares-Irlen syndrome patients with a mean age of 23.4 years (range, 13 to 42 years) with no history of neurological or psychiatric disorders were scanned using a 3T MR scanner (Siemens, Tim-Trio, Germany). Each patient underwent two sessions of fMRI imaging (before and after MISViS color-tinted lens application). The fMRI paradigm included a block design of 20 seconds of rest (cross), 20 seconds of activation (sentence reading), and ten blocks (a total of 200 echo-planar image volumes) repeated for each session. Data preprocessing and analyses were performed using the SPM8 software package. RESULTS: The reading speed of patients improved more than 20% while wearing the selected lenses. When compared to the before-lens session, the after-lens session identified significant regions of activation in the left middle and superior temporal gyri (paired t-test; maximal z score, 5.38; Montreal Neurological Institute coordinate, -60 / -39 / 0; threshold at p < 0.05; corrected for multiple comparisons using family-wise error). No region of activation at the same threshold was found in the before-lens session as compared to the after-lens session. CONCLUSIONS: In the current study, we confirmed activation in the left middle and superior temporal gyri during sentence reading after wearing color-tinted lenses. These results could explain the effectiveness of color-tinted lenses in patients with Meares-Irlen syndrome.
Adolescent ; Adult ; Brain/*pathology/physiopathology ; Color Perception/*physiology ; Dyslexia/*diagnosis/physiopathology ; *Eyeglasses ; Female ; Humans ; Magnetic Resonance Imaging/*methods ; Male ; Perceptual Disorders/*diagnosis/physiopathology ; Pilot Projects ; Reading ; Syndrome ; Vision Disorders/*diagnosis/physiopathology ; Young Adult