TABLE 2.
Brain functions in high altitude (HA) people.
| References | Location (altitude (m), duration) | Group: number (M/F) | Age (years) | Analysis | Techniques/tasks | Changed functions of the brain regions |
| Rostrup et al., 2005 | Chacaltaya Mountain (5260), 5 weeks | HA:11(6/5) longitudinal | 26.3 (22.4–34.4) | Whole brain analysis and ROI | visual task fMRI at 1.5 T machine/white rectangular checkerboard | Reduced 23% magnitude of the BOLD signal in visual task (p = 0.02). Decreased coefficient ADC (p < 0.05). |
| Yan et al., 2011b | Qinghai-Tibet Plateau (2527–3985), natives | HA: 12 SL: 11 |
22.4(20–24) 24.8(22–27) | Whole brain analysis | fMRI at 3.0 T machine/inspiration task | Lower CVR in the primary motor, visual cortex, somatosensory cortex, precuneus, posterior cingulate cortex, thalamus, and caudate; longer delayed hemodynamic response (p < 0.05). |
| Yan et al., 2011c | Qinghai-Tibet Plateau (2616–4200), natives | HA: 10 SL: 9 |
– | Whole brain analysis | visual task fMRI at 3.0 T machine/Food picture | Decreased BOLD signals in the middle, superior, and inferior frontal gyrus, insular cortex, cuneus, middle occipital gyrus, lingual gyrus, cingulate gyrus, and precuneus (p < 0.05); Increased BOLD signals in the inferior parietal lobule and cerebellar tonsil (p < 0.05). |
| Yan et al., 2011d | Qinghai-Tibet Plateau (2616–4200), natives | HA: 28(12/16) SL: 28(12/16) |
20(19–22) 21(19–22) |
Whole brain analysis and ROI | visual task fMRI at 3.0 T machine/2-Back verbal memory | Decreased BOLD signals in the inferior and middle frontal gyrus, middle occipital gyrus, lingual, the pyramis of vermis, and thalamus (p < 0.05). |
| Yan et al., 2011a | Qinghai-Tibet Plateau (2616–4200), natives | HA: 28(12/16) SL: 28(12/16) |
20(19–22) 21(19–22) |
Whole brain analysis and ROI | visual task fMRI at 3.0 T machine/2-Back spatial memory | Increased BOLD signals in the left pyramis, left superior temporal gyrus; Decreased BOLD signals in the left middle occipital gyrus (p < 0.05). |
| Wang et al., 2014 | Lhasa (3650, Tibet), 3 years | HA: 18(8/10) SL: 18(9/9) |
22(20–24) 23(21–24) |
ROI | visual task ERP/visual voluntary attention task | Found bilateral N1 activity; Smaller P3 under high perceptual load (p < 0.05). |
| Ma et al., 2015b | Lhasa (3650, Tibet), 2 years | HA:20(10/10) SL: 20(10/10) |
21.8(21–24) 22.8(21–24) |
ROI | visual task ERP/Go no go | Larger N2amplitude and smaller P3 amplitude in both the go and no go condition (p < 0.001). |
| Ma et al., 2015a | Lhasa (3650, Tibet), 2 years | HA: 17(8/11) SL: 17(9/8) |
20.75 (21–24) 21.78 (21–24) |
ROI | visual task ERP/Go no go | Larger ERN(p = 0.027) and CRN (p = 0.0001). |
| Ma et al., 2015c | Lhasa (3650, Tibet), 2 years | HA: 21(9/13) SL: 21(10/11) |
21.95 (19–24) 21.9(19–24) |
ROI | visual task ERP/Flanker | Smaller P3 amplitude in the incongruent target (p < 0.05). |
| Zhao et al., 2016 | Lhasa (3650, Tibet), 30 days | HA:25(25/0) longitudinal | 24.6 (21–28) | ROI | EEG | Decreased theta power after ascending to HA for 7 days (p < 0.05); Increased alpha and beta powers but decreased delta power in the middle posterior parietal and occipital areas after staying at HA for 30 days (p < 0.05); Decreased alpha power and increased beta power after return to sea level for 7 days (p < 0.05). |
| Chen et al., 2016a | Qinghai-Tibet Plateau (2300–4400),2 years | HA: 16 SL: 16 |
20.5(19–22) 19.9(19–22) |
Whole brain analysis | fMRI at 3.0 T machine/ Resting-state |
Increased Reho in the right inferolateral sensorimotor cortex (p < 0.05). |
| Zhang et al., 2017 | Qinghai-Tibet Plateau (2300–4400), 2 years | HA: 16 SL: 16 |
20.5(19–22) 19.9(19–22) |
Whole brain analysis | fMRI at 3.0 T machine/ Resting-state |
Increased ALFF in the bilateral occipital cortex, lingual gyrus, cuneus, and fusiform gyrus; Decreased ALFF in the right anterior insular cortex, extending to the caudate, putamen, inferior frontal orbital cortex, temporal pole, and superior temporal gyrus (p < 0.05). |
| Chen X. et al., 2017 | Lhasa (3650, Tibet), 0/1/2 years | HA: 69(48/21) longitudinal | (17–20) | Whole brain analysis and ROI | fMRI at 3.0 T machine/ Resting-state |
Decreased ReHo in the superior temporal gyrus, superior parietal lobule, anterior cingulate gyrus, and medial frontal gyrus; Increased ReHo in the hippocampus (p < 0.01). |
| Chen et al., 2016b | Qinghai-Tibet Plateau (2300–4400), 2 years | HA: 16 SL: 16 |
20.5(19–22) 19.9(19–22) |
Whole brain analysis | fMRI at 3.0 T machine/ Resting-state |
Increased VMHC in the bilateral visual cortex (p < 0.05). |
| Ma et al., 2018a | Lhasa (3650, Tibet), 2 years | HA: 29 SL: 29 |
(18–25) | ROI | visual task ERP/Visual voluntary attention | Slower response time in stimulus–driven attention, smaller P1/N1/P3 amplitude (p < 0.05). |
| Ma et al., 2018b | Lhasa (3650, Tibet), 2 years | HA:32 (15/17) SL:33(17/16) |
(19–22) | ROI | visual task ERP/Mental rotation | Slower response time in the mental rotation effect, larger rotation related negativity amplitude in each rotation angle condition (p < 0.05). |
| Zhang et al., 2018a | Lhasa (3650, Tibet), 2 years | HA: 20(10/10) SL:22(11/11) |
22.7(21–25) 23.0(23–25) |
ROI | visual task ERP/Visual search | Longer reaction time, lower N2pc amplitude, larger N2cc amplitude, higher MP amplitudes, and longer RAP latency (p < 0.05). |
| Zhang et al., 2018b | Qinghai-Tibet Plateau (2900–4200), natives | 4200m:23 (12/11) 3700m:21 (11/10) 2900m:23 (12/11) |
21(18–23) 21(18–23) 21(18–23) |
ROI | visual task ERP/Attention network | Decreased orienting and overactive executive functions in 4200m residents (p < 0.05). |
| Richardson et al., 2011 | La Paz (3700), natives | HA: 22(11/11) SL: 18(7/11) |
13–16 | ROI | EEG | Showed reductions in delta and beta frequency amplitudes (p < 0.05). |
| Ma et al., 2019b | Lhasa (3650, Tibet), 2 years | HA: 19(10/9) SL: 21(9/13) |
22.3 22.1(20–24) |
ROI | visual task ERP/2-Back verbal and spatial memory | Decreased late-positive potential amplitude in verbal and spatial tasks and larger P2 in spatial memory (p < 0.05). |
| Ma et al., 2019a | Lhasa (3650, Tibet), 2 years | 4500m:17(9/8) 3700m:18(8/10) 2700m:17(10/7) |
21.7 (21–24) 20.64 (18–24) |
ROI | visual task ERP/flanker | The N2 difference wave was smaller in the 4500m group than in the groups living below 4000 m (p < 0.05). |
| Wang et al., 2017 | Qinghai-Tibet Plateau (2200), 1 years | 19(9/10) longitudinal | 24.8 | Whole brain analysis and ROI | fMRI at 3.0 T machine/Resting-state | ALFF increased in Left middle frontal gyrus, decreased in the right lingual gyrus; ReHo increased in left superior frontal gyrus, decreased in right precuneus and parietal lobe (p < 0.05). |
| Li et al., 2021 | Lhasa (3650, Tibet), 2 years | HA:30(13/17) SL:30(16/14) |
(20–25) (17–22) | ROI | visual task ERP/mental rotation | Decreased P50 mean amplitude and the CDA amplitude of mental rotation mainly in the occipital, parietal and frontoparietal. Increased the beta/alpha power in mental rotation and the theta/alpha/beta power in CDA; |
| Xiang et al., 2021 | Lhasa (3650, Tibet), 2 years | HA:32(15/17) SL:32(17/16) |
(19–22) | ROI | visual task ERP/mental rotation | Decreased the alpha and the beta ERD within the time window (400–700 ms) (p < 0.01). The decreased ERD was observed at the parietal–occipital regions within the alpha band and at the central–parietal regions within the beta band (p < 0.01). |
| Xin et al., 2020 | Lhasa (3650, Tibet), 2 years | HA:69(48/21) longitudinal | 18.2(17–19) | Whole brain analysis | fMRI at 3.0 T machine/Resting-state | Decreased degree centrality and nodal efficiency in the insula, cingulum, hippocampus, amygdala, putamen, thalamus, temporal, and vermis; Increased degree centrality and nodal efficiency in the frontal, occipital, parietal, and angular (p < 0.05). |
| Chen et al., 2021 | Lhasa (3650, Tibet), 1 and 2 years | HA:69(48/21) longitudinal | 18.2(17–19) | Whole brain analysis | fMRI at 3.0 T machine/Resting-state and stroop | Decreased degree of co-activation within the left/right frontoparietal network, sensorimotor network, and auditory network after exposure. Which was found in left angular gyrus, in the right frontoparietal network, in left precentral gyrus and postcentral gyrus, in left middle frontal gyrus and left superior temporal gyrus (p < 0.001). |
| Forster et al., 1975 | 4300 (Mt. Evans, colo), 12 days | 7(7/0) | - | ROI | EEG/visual evoked responses | In three subjects, EEG frequency was increased, amplitude decreased. In 4 subjects, visual evoked responses decreased. |
| Qiu et al., 2021 | Dangxiong (4300), 1 month | 23(12/11) longitudinal | 19.4(19–21) | ROI | visual task ERP/clock | Decreased N1 and P3 at occipital electrodes. (p < 0.05) Decreased theta power. (p < 0.05) |
| Nisha et al., 2020 | 6096, mean 10.5 h/annum | HA:4(3/1) SL:4(3/1) |
37.23 | Whole brain analysis | visual task fMRI at 3.0 T machine/working memory | Showed significant activation in the right middle frontal gyrus (p < 0.05). |
ALFF, amplitude of low-frequency fluctuations; BOLD, blood oxygenation level dependent; CDA, contralateral delay activity; CRN, correct-related negative; CVR, cerebral vascular reactivity; ERN, error-related negative; ERD, event-related desynchronization; ERP, event-related potential; HA, high altitude; MRI, magnetic resonance imaging; Reho, regional homogeneity; T, tesla.