| Objective : By using the event related potentials,with different visual angled and direction of the opening of the letter "E" as the stimulus pictures and a variety of experimental schemes are designed,We aimed to make a comprehensive analysis of the exogenous and endogenous components of ERP during visual stimulation and to explore the cognitive process of the brain for the visual acuity.At the same time,we traced the source of ERP components to understand brain regions involved in different stages of visual processing and then provided an objective electrophysiological index for evaluating visual acuity.By using a variety of color experimental models and analyzing the characteristics of ERP under the stimulation of three colors of red,green and yellow,we aimed to explore the brain’s processing mechanism of color vision and the location characteristics of brain regions from three aspects of color perception,discrimination and recognition,so as to provide an electrophysiological index for objective evaluation of color vision function.Methods : There were 56 students who had no other ophthalmopathy except for ametropia,of which 26 uncorrected visual acuity was 0.1,and the corrected visual acuity of all the subjects was 1.0.(1)The subjects of the visual acuity ERP experiment were those who had uncorrected visual acuity of 0.1.The stimulus picture is the "E" letter of different opening directions in the international standard visual acuity chart and the visual angle is adjusted according to the requirements of each experiment.In the first group,two target stimuli visual Oddball mode were used.The subjects were tested with corrected visual acuity and the monocular and binocular were detected.The characteristics of N1,P2,N2 and P3 were analyzed.In the second group,the single target stimulus visual Oddball mode was applied and there were four modules.The standard stimulus of each module was the same and the visual angle of target stimulus were 1degree 15 ’,55’,24 ’,and 15’ respectively.The subjects were tested with uncorrected visual acuity and the characteristics of P3 were analyzed.In the third group,the visual Go/Nogo mode was adopted and the visual angle of Nogo stimulation were 1 degree 15 ’,55’,24 ’,15’.The subjects were tested with uncorrected visual acuity and the characteristics of Nogo-P3 were analyzed.(2)The subjects with color vision ERP were tested with corrected visual acuity and the monocular and binocular were detected.The experimental stimulus were squares with a color of white,red,green and yellow and the visual angle were 4 degrees.The first experiment was that the pictures were stimulated separately and the color of the pictures was red,green and yellow.The characteristics of the N1 were analyzed.The second experiment used a Oddball model,with a single target stimulus,including three modules.The standard stimulus for each module was a white figure and the three colors of red,green and yellow were the target stimuli respectively.The characteristics of N1,P2,N2 and P3 were analyzed.The third experiment used Oddball mode,including three target stimuli,white figure as standard stimuli and red,green and yellow color patterns as target stimuli.The characteristics of N1,P2,N2 and P3 were analyzed.Results:(1)Results of visual acuity ERP in each experimental model:(1)There was no statistical difference in the P3 peak latency between the 1 degree 15 ’group and the 55’group,the 24 ’group and the 15’ group(P>0.05).There was statistical difference in the P3 peak latency between the 55 ’group and the 24’ group,and the 55 ’group was higher than the 24’ group(P<0.05).There was no statistical difference in P3 amplitude between modules(P>0.05).(2)There was no statistical difference in the Nogo-P3 peak latency between the 1 degree 15 ’group and the 55’ group,the 24 ’group and the 15’group(P>0.05).There was statistical difference in the Nogo-P3 peak latency between the55 ’group and the 24’ group,and the 55 ’group was higher than the 24’ group(P<0.05).There was no statistical difference in Nogo-P3 amplitude between modules(P>0.05).(3)There were no statistical differences in peak latency and amplitude between two kinds of target stimuli,including N1,P2,N2 and P3,between the left eye,the right eye and the both eyes(P>0.05).There were no statistical differences in the amplitude of N1,P2,N2 and P3 caused by two kinds of target stimuli between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes(P>0.05).There were no statistical differences between the left eye and the right eye in the peak latency of N1,P2,N2 and P3 and there were statistical differences between the left eye and the both eyes,the right eye and the both eyes(P<0.05).The peak latency of N1,P2 and P3 in binocular were higher than that of monocular and N2 was lower than that of monocular.(2)Results of colour vision ERP in each experimental model:(1)There was no statistical difference in the peak latency and amplitude of the N1 with colour stimulus of red,green and yellow between the left eye,the right eye and the both eyes(P>0.05).Under three kinds of colour stimulus,for N1,there was no statistical difference in the peak latency between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes and the amplitude between the left eye and the right eye(P>0.05).The N1 amplitude was statistically significant between the left eye and the both eyes,the right eye and the both eyes and the binocular was higher than the monocular(P<0.05).(2)There were no statistical differences in the peak latency of the N1 and P2 with colour stimulus of red,green and yellow between the left eye,the right eye and the both eyes(P>0.05).The amplitude of N1 and P2 were statistically different from the three color stimuli(P<0.05).For N1,the Yellow target was the highest,the red was the second,and the green was the lowest.For P2,the green target was the highest,the red was the second,and the yellow was the lowest.There was no statistical difference in the peak latency and amplitude of the N1 and P2 with three kinds of color stimulation between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes(P>0.05).There was statistical difference in the peak latency of the N2 with colour stimulus of red,green and yellow between the left eye,the right eye and the both eyes(P<0.05).In the monocular test,the yellow was the shortest,the green was the longest,and the red was between the two and in the binocular test,the yellow was the longest,the red and green trend was the same as that of the monocular.There was statistical difference in the amplitude of the N2 with three kinds of color stimulation between the left eye,the right eye and the both eyes(P<0.05).The yellow was the highest,the red was the second,the green was the lowest and the monocular and binocular were in the same trend.For the N2 peak latency of three color stimuli,there was no statistical difference between the left eye and the right eye and there was statistical difference between the left eye and the both eyes,the right eye and the both eyes(P<0.05).In red and green experiments,the peak latency of N2 in binocular was less than that of monocular and the yellow was the opposite.There was no statistical difference in the amplitude of the N2 with three kinds of color stimulation between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes(P>0.05).There was no statistical difference in the peak latency and amplitude of the P3 with colour stimulus of red,green and yellow between the left eye,the right eye and the both eyes and the same result between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes(P>0.05).(3)The result trend of N1,P2 and N2 was the same as that of experiment two.For P3,there was no statistical difference in the peak latency with colour stimulus of red,green and yellow between the left eye,the right eye and the both eyes(P>0.05).There was statistical difference in the amplitude of the P3 and the red was the highest,the yellow was the second,the green was the lowest(P<0.05).There was no statistical difference in the peak latency and amplitude of the P3 with colour stimulus of red,green and yellow between the left and the right eye,the left eye and the both eyes,the right eye and the both eyes(P>0.05).Conclusion :(1)Under the Oddball experimental mode,P3 reflected the cognitive response of the subjects to target stimuli,and the feigned blind of the subjects could be judged according to the presence of P3 component.(2)There was differences in ERP components between monocular and binocular vision.In forensic clinical identification,it could be used to judge whether the subjects cooperate or not.(3)At the visual recognition level,the characteristics of P3 and Nogo-P3 components could be used for objective assessment of visual acuity.(4)At the level of color perception,the binocular summation might also occur in the color vision.(5)Different color processing mechanisms might exist at different stages of color perception.(6)The brain had different psychological effects on different colors.(7)The differences of ERP components between monocular and binocular color vision could provide basic data for objective assessment of color vision. |
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