| Background At present,learning disabilities has become a common problem cross the whole world.Scholars,teachers and parents in our country also pay high attention to this problem.Modern cognitive science did much research on learning disabilities problem covering perception,attention,memory,research etc. In the research area of learning disabilities,most research focused on the stability of attention and divided attention.Besides,research on attention span and attention shifting were almost behavioral studies.Based on what i have mentioned above,this study attempts to combine ERP technique which has a feature of high temporal rate to explore the characteristics of visual attention span and attention shifting in children with learning disabilities and the neurophysiological mechanisms during the process.Objectives This study aims to explore the behavioral characteristics and neurophysiological mechanisms in children with learning disabilities including dyslexia and dyscalculia.Methods Use cluster sampling method choose all the junior school freshmen from one junior middle school in Xinxiang, then the students were tested with learning adaptive tests,learning difficulties screening scale,Raven standardized intelligence tests and considering the students’ latest twice final examination performance, gradually selected 18 dyslexic children,18 dyscalculia children,18 control group children with a balanced gender ratio.Experiment 1:This experiment adopts fixed-location center cuing paradigm, using 3 (dyslexic group, dyscalculia group, control group) ×2 (attention span:large, small) ×3(brain regions:the parietal,occipital,occipital) three factors mixed design.Subjects were between-subjects design and the attention span,brain regions were within-subjects design. Experiment 2:This experiment adopts center cuing paradigm,using using 3 (dyslexic group, dyscalculia group, control group) ×2 (consistency:consistent, inconsistent) ×4 (brain regions:the central-top lobe, parietal lobe,top-occipital lobe, occipital lobe) three factors mixed design.Subjects were between-subjects design and the attention span,brain regions wereResultsExperiment 1:Having a LSD test on reaction time, under large and small attention span condition,the average reaction time of dyslexic children was significantly longer than that of the control group children(P=0.021,P=0.045);the average reaction time of dyscalculia children was shorter than that of control group children, but has not reach the significance level(P=0.119,P=0.445). Three groups children’ average accuracy under small attention span was significant higher than that under the large attention span(t=6.644, df=17, P=0.000; t=7.007,df=17, P=0.000; t=8.475, df=17, P=0.000). Under the small attention span or the large small attention span, three groups children have no significant difference on average accuracy [F(2,51)=0.002,P=0.998;F(2,51)=0.005,P=0.830].2. On P1 amplitude, learning disabilities group children and control group children both have attention span grade effect,that was, amplitude increased with attention span decreased[F(1,51)=51.906,P<0.001,η2=0.222]; under small and large attention span condition, on top lobe,top-occipital lobe, occipital lobe,dyslexic children induced a greater P1 amplitude than that of the control group children. The average amplitude of dyscalculia children was higher than that of the control group,but was not reach the significance level. Three groups children’ P1 latency had no significance under small or large attention span[F(1,17)=2.473,P=0.134,η2=0.127].N1 amplitude increased with the decrease of attention span[F(2,51)=34.485,P<0.01,η2=0.403],then having a LSD test,under small and large attention span condition,at parietal lobe, the average Nl amplitude was significantly smaller than that of the control group children(P=0.029;P=0.028). The average Nl amplitude of dyslexic children was smaller than that the control group children but hasn’t reached the significance level.Experiment 2:1. Under consistent condition, having a LSD test on the average reaction time, the reaction time of the control group children was significantly longer than that of the dyslexic children and the dyscalculia children(P=0.010;P=0.005). Three groups children average accuracy had no significant difference,but there was a tendency that the average accuracy of control group children was higher than the learning disabilities children. Under inconsistent condition, the average reaction time of control group was significantly higher than that of the dyscalculia group children(P=0.018). The average reaction time of control group tends to be higher than that of the dyslexic children group,but has not reached the significance level. There was a significant difference on the average accuracy of three groups children[F(2,50)=4.301,P=0.019]. The average accuracy of control group children was significantly higher than the dyscalculia group children and the dyslexic children group(P=0.009,P=0.027).2. Under inconsistent condition, on parietal-occipital region,the N1 amplitude of dyscalculia and dyslexic children group were significantly greater than that of the control group(P=0.005;P=0.017). There was no significance on latency(P=0.206; P=0.250). Under inconsistent condition,on parietal-occipital region,the N1 amplitude of dyscalculia children group was significantly greater than that of the control group(P=0.038). The N1 amplitude of dyslexic children group tends to be greater than that of the control group but has not reached the significance level(P=0.082). Under consistent and inconsistent condition,three groups children had no significant difference on latency.3. Under consistent condition, at central parietal lobe,the P3 amplitude of control group children was significantly greater than that of the dyslexic and dyscalculia group children(P=0.028;P=0.018). Under inconsistent condition, at parietal lobe,the P3 amplitude of control group children was significantly greater than that of the dyslexic and dyscalculia group children(P=0.021;P=0.023). Under consistent condition, at parietal lobe,parietal-occipital lobe, the P3 latency of dyslexic was shorter than that of the control group(P=0.003;P=0.020).The P3 latency of dyslcalculia group children was shorter than that of the control group but has not reached the significance level. Under inconsistent condition,at the central parietal lobe,parietal lobe,parietal-occipital lobe,occipital lobe, the average P3 latency was significantly shorter than that of the dyslexic group children(P=0.036;P=0.039; P=0.011;P=0.007). The average P3 latency was shorter than the control group but has not reached the significance level.Conclusions1. Children with learning disabilities exist visual attention span grade effect. But there is a deficit on their visual attention span which we speculate was caused by the inadequate basic perceptual processing ability and deficient divided attention.2. Children with learning disabilities exist cuing effect. But there is a deficit on their attention shifting ability which we speculate was caused by the deficit in the parietal-occipital lobe function and occipital lobe function. |
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