Effect of altitude on the spatiotemporal signal characteristics of inversion face recognition

Abstract

High-altitude environments, can significantly impact cognitive functions, yet the neural mechanisms underlying altitude-induced changes in face recognition remain largely unexplored. This study aimed to examine the impact of high-altitude hypoxia on face recognition processes, with a specific focus on the modulation of the face inversion effect in event-related potentials across different altitude levels. A total of 120 participants were recruited and divided into four groups based on altitude: 347 m (low-altitude control), 2950 m, 3680 m, and 4530 m (high-altitude groups), with 30 participants in each group. Electroencephalography (EEG) was used to record brain activity, and event-related potentials components (P1 and N170) were analyzed to assess the effects of altitude on face processing, particularly regarding the face inversion effect. A significant altitude-dependent reduction in P1 amplitude was observed, with the 3680 m and 4530 m groups showing significantly lower amplitudes compared to the 347 m group (p < 0.05), and inverted faces elicited greater P1 amplitudes than upright faces (p = 0.035). N170 amplitude was significantly more negative for inverted faces compared to upright faces (p < 0.001), while the 4530 m group exhibited earlier N170 latencies than the other altitude groups (p < 0.05), suggesting possible neural adaptation to chronic hypoxia. The sLORETA results revealed progressive temporal lobe reorganization: the 4530 m group exhibited enhanced activation in superior temporal gyrus during inverted face processing, contrasting with diminished responses at moderate altitudes (3680 m). These findings provide neurophysiological evidence that high-altitude hypoxia significantly modulates face recognition processes, particularly the face inversion effect. The observed altitude-dependent alterations in ERP components suggest that hypoxia impacts both early sensory encoding (P1) and higher-order configural processing (N170).