Hemodynamic variations in resting-state cerebral functional networks between Tibetan and Han male athletes assessed by fNIRS

This study seeks to compare systemic variations in functional connectivity within core motor brain regions at rest between young male soccer players from the indigenous Tibetan population of the Tibetan Plateau and their counterparts from the Han population of the plains, to elucidate the intrinsic relationship between specific ethnic backgrounds and central nervous system hemodynamic phenotypes. This study recruited 44 male youth soccer players at the national second-tier level (23 native Tibetans from Tibet and 21 native Han Chinese from Harbin). Data collection occurred at a low altitude in Harbin, Heilongjiang Province, roughly 150 m above sea level, with Tibetan subjects tested within 4 weeks of their migration from the plateau to the plains. Functional near-infrared spectroscopy (fNIRS) was employed to gather 8 min of resting cerebral hemodynamic data from the subjects. Utilizing oxygenated hemoglobin (HbO 2 ) as the principal indicator and deoxygenated hemoglobin (HbR) as an ancillary indicator, we conducted a one-way analysis of covariance (ANCOVA) to evaluate connectivity disparities among the prefrontal cortex, premotor and supplementary motor areas, and primary motor cortex, while rigorously controlling for systemic peripheral physiological covariates, including resting heart rate (HR) and oxygen saturation (SpO 2 ). 1. Based on HbO 2 signals, in the Tibetan group, the PFC-PMC&SMA and PMC&SMA-M1 regions across the entire brain, as well as the PFC_L-PMC&SMA_L,PFC_R-PMC&SMA_L,PMC&SMA_L-PMC&SMA_R,PMC&SMA_L-M1_L, and PMC&SMA_L-M1_R regions in both hemispheres were significantly lower than those in the Han group; 2. Based on HbR signals, the Tibetan group showed higher functional connectivity strength than the Han group only in the PFC_R-PMC&SMA_R region. Han athletes exhibit strong functional connectivity patterns related to HbO 2 , reflecting the classic patterns of brain remodeling in the prefrontal and motor regions resulting from long-term specialized training in a lowland environment with normal oxygen levels; In contrast, the pattern of widespread low HbO 2 connectivity accompanied by localized high HbR connectivity in Tibetan athletes may be associated with the underlying adaptive background of populations native to the plateau, theoretical brain energy-saving strategies involving low metabolism, and the characteristics of central hemodynamic fine-tuning during the period of de-adaptation following descent from the plateau.