The Effects Of Different Altitudes On The Cognitive Of Plateau Warriors: An ERP Study

The plateau environment is characterized by hypoxia,dry,cold,strong solar radiation,with big difference of temperature between the day and at night etc.,which has a great impact on the physical and mental health of the human body.However,it has not reached a consistent conclusion about the effects of long-term or short-term exposure to hypoxia on human cognitive.Some studies found that the altitude environment has significant effects on people's cognitive functions,such as short-term memory,attention span and attention transition,thinking judgment,reaction time,etc.,which can reduce psychological functions,affect psychophysiological adaptation,and then affect work performance.However,some other studies indicate that transient or intermittent hypoxic exposure may improve one's spatial memory ability.The cognitive ability of adolescents who live in the plateau area for a long time is not significantly different from that of adolescents living in the plain area.In recent years,with the modernization of national defense and the reform of the army,more and more officers and soldiers are stationed in high-altitude areas.For these troops who are not stationed at high altitudes,plateau training for a few months also is required.As a special task group,their living conditions and working modes are quite different from general people.Since cognitive functions are so import for the soldiers to finish military tasks,such as executive inhibition control and involuntary attention,it is an urgent issue to explore the influence of hypoxic exposure on their cognitive functions.ObjectiveAt present,there have been a large number of ergonomic studies on the effect of hypoxia exposure on the cognitive ability of military personnel,but there are few reports exploring the event-related potential technology to collect more objective indicators.The purposes of this study were:(1)to explore the influence of different altitudes on the inhibition control ability of soldiers;(2)to explore the influence of different altitudes on soldiers' non-attentional tasks.MethodsThis study is divided into two parts.Study 1: Convenient cluster sampling method was adopted.Twenty subjects were selected from three medium elevations as the experimental groups(respectively plateau group1(2950m),plateau group2(3680m),plateau group3(4530m))and twenty subjects from the low altitude(< 500m)were selected as the plain control group.The four groups all carried out the event-related potential test of the classic Go/NoGo task.Then multivariate analysis of variance of repeated measurements was carried out,to explore the influence of different altitude on the inhibition and control ability of plateau warriors.Study 2: Both sampling method and subjects are the same as study 1.The event-related potentials of the four groups were tested in the classic face inversion task.Then multi-way Repeated Measures Anova was performed,to explore the effects of different medium altitudes on the non-attentional tasks of soldiers.Results1.Behavioral results of Go/NoGo.Univariate Anova was used to compare the correct hit rate,false alarm rate and correct hit response of the four groups in the Go/NoGo task.These three indicators had no significant differences among the four groups.2.Amplitudes and latencies of N2 and P3 in Go/NoGo.N2 amplitude of the plain control group was significantly lower than those of the three plateau groups,and there were no significant differences among the three plateau groups.The N2 peak latency of plateau group2 was significantly shorter than those of the control group and plateau group3.The P3 peak amplitude of the plain control group was significantly greater than those of the three plateau groups(all p<0.001),while there were no significant differences among the three plateau groups.The P3 peak latency of plateau group1 was significantly earlier than those of the other three groups.3.ERP results in face inversion task.P1 was induced earlier in the plateau group1 than those in plateau group2 and plateau group3(p=0.039,p<0.001).Both upright and inverted faces induced later N170 for plateau group3 than the control group(p=0.004,p=0.037).Inverted faces induced later N170 for plateau group3 than plateau group2(p=0.007).Smaller EPN is induced for plateau group2 and plateau group3 than the control group and plateau group1(p=0.022 and p=0.019,p=0.004 and p=0.003).The mean amplitude of LPP is bigger than the control group and plateau group1(p=0.001,p=0.017).Conclusion1.The effect of hypoxic environment on simple cognitive function is relatively small,which is difficult to be observed in behavioral perspective.2.According to the ERP data,all three plateau groups encountered impairs in the inhibitory control function and the plateau group1 encountered more.3.In involuntary attention task,the plateau hypoxic environment may influence the early perception of stimuli and higher cognitive function is gradually involved in information processing of stimuli.It is suggested that the effect of mild hypoxia exposure on cognitive function is not easy to be detected,but one should maintain mental health and pay attention to the regulation of emotional stability in mild hypoxia ahead of time.With the increase of altitude,the speed and accuracy of the recognition of stimuli will gradually decrease,and the identifying and classifying different objects will become more difficult.As a result,more psychological resources should be invested when performing relevant tasks.In addition,it may require more manpower,materials and financial resources to complete the military mission in the plateau environment than in the plain areas.