How expertise changes cortical sources of EEG rhythms and functional connectivity in divers under simulated deep-sea conditions.

Although the recent years have witnessed a growing interest in functional connectivity (FC) through brain sources, FC in extreme situations has not been completely elucidated. This study aimed at investigating whether the expertise acquired during deep-sea diving is reflected in FC in a group of professional divers (PDs) compared with a group of new divers (NDs) and how it could affect concentration and stress levels. The source of brain frequency rhythms, derived by electroencephalography (EEG) acquisition in a hyperbaric chamber, were extracted in different frequency bands and the corresponding FC was estimated in order to compare the two groups. Results highlighted a significant decrease of alpha source in PDs during air breathing and a significant increase of the upper beta source over central areas at the beginning of post-oxygen air, as well as an increase of beta FC between fronto-temporal regions in the last minutes of oxygen breathing and in the early minutes of post-oxygen air. This provides evidence in support of the hypothesis that the experience and expertise differences would modulate brain networks. These experiments provided the unique opportunity of investigating the impact of the neurophysiological activity in simulated critical scenarios in view of the investigation in real sea-water experiments.