Reversible brain functional alterations induced by Short-Term high altitude exposure.

High altitude hypoxia is known to induce both physiological and neural alterations, however, the dynamics of brain functional changes following short-term exposure remain unclear. This study aimed to investigate the physiological and neural effects of short-term high altitude exposure and subsequent recovery at low altitude. We assessed hematological parameters and brain functional activity at three time points: one week before ascent, on day 30 of high altitude exposure, and two months after returning to sea level. After 30 days at high altitude, red blood cell count and hemoglobin increased, with the SpO2 decreased; the regional homogeneity (ReHo) were significant differences in the cerebellum posterior lobe, brainstem, fusiform, lingual gyrus, and precentral gyrus. The voxel-mirrored homotopic connectivity (VMHC) were significant differences in the occipital and postcentral cortices. Edge-level functional connectivity (FC) analysis revealed reduced connectivity within the visual network (VN), sensorimotor network (SMN), subcortical network (SCN), and frontoparietal network (FPN), as well as between the SMN and ventral attention network (VAN), and between the FPN and default mode network (DMN). Our findings revealed that both physiological indices and brain functional measures (ReHo, VMHC, and FC) showed a similar pattern of recovery, returning to baseline levels after returning to low altitude for two months. These results provide new evidence for the reversibility of brain functional alterations following short-term high altitude exposure.