ABSTRACT
Objective:To investigate the neural mechanism of long-term exposure to high altitudes environment on the processing stage of perceptual closure.Methods:A cross-sectional study was conducted. Thirty college students who first entered the plateau area (at an altitude of 3 658 m) and had lived in high-altitude areas for two years were selected as high altitude group (HA group), and 29 college students matched in age, gender and education level who had never been to the plateau area were selected as sea level group (SL group). The differences of basic physiological parameters were compared between the two groups.The face pairwise comparison paradigm was applied in the subjects of the two groups and the differences between the two groups were compared by event-related potentials (ERPs) technology. SPSS 22.0 software was used for statistical analysis, and the mean ± standard deviation was used for statistical description. Independent sample t test was used for comparison of physiological data between the two groups, and repeated measurement variance analysis was used for ERP data. Results:The physiological results revealed that the HA group had a higher pulse rate((86.71±10.82)/min, (75.97±11.28)/min ; t=-3.19, P=0.002) and diastolic blood pressure than the SL group ((75.93±9.19)mmHg, ( 68.59±11.42) mmHg ; t=-3.20, P=0.002). The oxygen saturation level was significantly lower than that of SL group ((90.77±2.25)%, (98.31±1.56) %) ; t=14.00, P<0.001). In the face pairwise comparison paradigm test, the main effect of P1 latency of ERP was significant.Compared with SL group, HA group showed significantly shortened latency of P1 ((105.10±15.59) ms, (128.35±14.40)ms, P<0.001). The main effect of group of N170 amplitude was significant, HA group was larger than that of SL group((-7.57±3.83) μV, ( -5.11±3.26) μV, P=0.005). The interaction effect between group and hemisphere of NCL amplitude was significant ( F(1, 57)=9.72, P=0.003). Simple effect test showed that the amplitude on the right hemisphere of SL group was significantly larger than that on the left hemisphere((0.46±1.31) μV), (1.16±1.33) μV ). The latency of P1 was significantly correlated with heart rate( r=-0.46, P<0.01), oxygen saturation level( r=0.64, P<0.01) and diastolic blood pressure( r=-0.26, P=0.049). Conclusion:After long-term exposure to high altitude, the neural response related to early visual perception is faster. More psychological resources are recruited during the face structural encoding stage. Contra-lateral compensating effect appeares in the stage of perceptual closure.
ABSTRACT
Objective To analyze the diagnostic value of diffusion tensor imaging(DTI)and diffusion tensor tractography(DTT) in viral encephalitis at 3.0T magneton. Methods 25 patients with viral encephalitis confirmed by clinic and 25 age-match healthy patients were examined by conventional MRI and DTI. The average diffusion coefficient (ADC) map, fractional anisotropy (FA) map and diffusion tensor tractography (DTT) was acquired through image post processing technique. The ADC value, FA value of lesions and normal tissues were measured by region of interest (ROI) with the same standard and the results were statistically analyzed.Results In the acute stage of viral encephalitis: The ADC values were significantly lower than that in normal tissues of control group (P<0.01), FA values of lesions were higher than that of control group and had no statistical significance (P＞0.05). In the subacute and chronic stage of viral encephalitis: The ADC values were higher than that of control group and had statistical significance(P＜0.01), FA values of lesions were significantly lower than that of control group(P<0.05). DTT imaging showed infiltrative changes of white matter fibers in the lesion areas.Conclusion DTI and DTT technique may provide some complementally informations and clinical diagnostic value for viral encephalitis.