轻、中度缺氧应激时声强对脑认知功能的影响

Effect of light and moderate hypoxia stress on brain event related potentials and reaction time in different sound intensities

目的 通过分析在 4种不同高度和 5种不同声强条件下 P30 0 的潜时及波幅 ,反应时 ,得出轻、中度缺氧条件下最佳声强值 .方法 14名受试者在地面及 15 0 0 m,30 0 0 m,45 0 0 m三个模拟高度 (吸低氧混合气体 )分别进行 5种不同声强值 (5 5 ,6 0 ,70 ,80 ,85 d B)的听觉 oddball测试 ,记录脑电图 (EEG)、反应时 (RT)及主观感觉 ,EEG经平均叠加处理提取出脑事件相关电位 (ERP)中的 P3波幅、潜时 .以 P3潜时和 RT为主要指标评定脑认知能力 ,结合主观评价确定最佳声强值 .结果 P30 0 潜时及 RT,在地面及 15 0 0 m ,5种听觉oddball任务声强为 5 5 d B时的 P30 0 潜时及 RT明显长于其它 4种声强 (P<0 .0 1) ,而其余 4种声强间则无明显差别 .在 30 0 0m,5 0 0 0 m,声强为 70 ,80 ,85 d B时 P30 0 潜时及 RT明显短于5 5 d B及 6 0 d B的 P30 0 潜时和 RT (P<0 .0 1) ,而主观评价反映 80 ,85 d B声强刺耳 ,难以忍受 .结论 在地面及 15 0 0 m轻度缺氧情况下最佳声强值为 6 0～ 70 d B;在 30 0 0 m及 5 0 0 0m中度缺氧条件下 ,最佳声强值为 70～ 80 d B,此时 P3潜时及RT最短 ;

AIM To explore the most suitable sound intensity for man in light and moderate hypoxia stress. METHODS Fourteen healthy and well trained students were selected assubjects. They were arranged to perform audio oddball tasks of 5 different sound intensity(55, 60, 70, 80, 85 dB) at four attitudes(Ground, 1500 m, 3000 m, 4500 m). 486 IBM Personal computer was used to produce different sound intensity tones, which were broadcasted to subjects by ear phone. meter was used to measure sound intensity. The subjects breathed air or low oxygen mixture to simulate different attitudes. EEG data and reaction time (RT) were collected. P 300 waves of event related potential (ERP) were extracted. P 300 latency and RT, as the main indexes to measure the brain cognitive response speed, were analysed by using a 2 factor (contrast×attitude) analysis of variance. Finally subject feelings were recorded as another important index of evaluation. RESULTS At ground and 1500 m when sound intensities were 60, 70, 80, 85 dB, P 300 latency and RT were significantly shorter compared with 55 dB ( P <0.01). But there were no significant differences of P 300 latency and RT among them. At 3000 m and 1500 m when sound intensities were 70, 80, 85 dB, P 300 latency and RT were significantly shorter compared with the other two's ( P <0.01) while significant distinctions among theirs were not found. According to subject feelings sound intensities above 80 dB were unbearable. So the most suitable sound intensity for ground and light hypoxia is 60~70 dB; while for moderate hypoxia it maybe 70~80 dB. CONCLUSION In light hypoxia stress the most suitable sound intensity is 60~70 dB whereas in moderate hypoxia it is 70~80 dB.