Disruptions in brain functional connectivity: The hidden risk for oxygen-intolerant professional divers in simulated deep water

In this study, we investigated the effects of oxygen toxicity on brain activity and functional connectivity (FC) in divers using a closed-circuit oxygen breathing apparatus. We acquired and analyzed electroencephalographic (EEG) signals from a group of normal professional divers (PD) and a group that developed oxygen intolerance, i.e., oxygen-intolerant professional divers (OPD), to evaluate the potential risk of a dive and understand the physiological mechanisms involved. The results highlighted a significant difference in the baseline levels of $\alpha$ rhythm between PD and OPD, with PD exhibiting a lower level to counteract the effects of increased $O_2$ inhalation, while OPD showed a higher level that resulted in a pathological state. Connectivity analysis revealed a strong correlation between cognitive and motor regions, and high levels of $\alpha$ synchronization at rest in OPDs. Our findings suggest that a pathological condition may underlie the higher $\alpha$ levels observed in these individuals when facing the stress of high $O_2$ inhalation. These findings support the hypothesis that oxygen modulates brain networks, and have important implications for understanding the neural mechanisms involved in oxygen toxicity. The study also provides a unique opportunity to investigate the impact of neurophysiological activity in simulated critical scenarios, and opens up new perspectives in the screening and monitoring of divers.