The Spontaneous Fluctuations In Brain Activity And Dynamic Characteristics Of Mental Rotation In Hypoxic Exposure:Evidence From EEG Activity

Long-term hypoxia exposure affects spontaneous fluctuations in brain activity and cognitive ability.In our study,EEG was used to collect resting and task state data from college students in Guangzhou and Tibet.The resting state data were processed by source localization method to explore the spontaneous fluctuations in brain activity exposed to hypoxia.Recently,researches show that:(1)The cortical activity(frontal lobe,parietal lobe)of low band and cortical activity(occipital lobe)of beta band were significantly decreased in migration to high-altitude group.(2)Compared with low altitude group,the cortical activity(frontal lobe,parietal lobe and temporal lobe)of delta band,cortical activity(frontal lobe,parietal lobe and occipital lobe)of alpha band and cortical activity(parietal lobe and occipital lobe)of theta and beta band were significantly decreased in high altitude local residents.(3)Compared with local residents at high altitudes,cortical activity(frontal lobe)of delta band decreased significantly in migration to high-altitude group.Our results demonstrate that:the brain central nervous activity decreased in hypoxic exposure;the brain was malleabled and can self-regulate its activity to adapt hypoxic environment.Through time-frequency characteristics and source localization method,exploring the cortical activity of mental rotation in hypoxic exposure.Researches show that:(1)The main effect of hypoxia was significant(F(1,63)=5.44,p=.02,?~2=.08),high altitude group(973.17±23.5ms)of the mental rotation reaction significantly greater than low altitude group(896.23±23.14ms);The main effect of angles were significant(F(5,315)=181.49,p<.001,?~2=.742);main effect of material type was significant(F(1,63)=459.56,p<.001,?~2=.0879),normal letters were less than mirror letters.(2)Compared with the low-altitude group,the ERD attenuation in the high-altitude group during the 400-700ms phase of the mental rotation task was observed,alpha band energy of the high-altitude group(-1.278±.119dB)were significantly higher than low-altitude subjects(-2.781±.118dB),the energy of the high-altitude subjects(-1.475±.07dB)at beta band was also significantly higher than low-altitude group(-2.401±.069dB).(3)The cortical activity of frontal,parietal,temporal and occipital cortex decreased in the high-altitude group.Our results demonstrate that:mental rotation effect delay of hypoxic exposure may be related to the weakening of alpha and beta bands ERD phenomenon and cerebral cortex activation decreased.Combining the results of resting state and task state,it was further speculated that activity of occipital cortex(BA17,18 and 19)of beta band and activity of parietal cortex(BA40)of delta,theta and alpha bands were the key cortical regions that affected the performance of mental rotation under hypoxia exposure.