Reduction in EEG theta power as a potential marker for spatial disorientation during flight

During flight, spatial disorientation (SD) commonly occurs when a pilot's perception conflicts with the aircraft's actual motion, attitude, or position. A prevalent form of SD is the somatogyral illusion, which is elicited by constant speed rotation and causes a false perception of motion in the opposite direction when the rotation ceases. This research aimed to investigate changes in brain activity that occur when experiencing a somatogyral illusion by simulating conditions closely mimicking flight conditions to gain insight into how to better manage this illusion during flight. In the study, 23 volunteers were isolated from external stimuli to promote somatogyral illusion induction while seated in a Barany (rotating) chair. The study employed electroencephalogram (EEG) and eye-tracking glasses to monitor brain activity and eye movements, respectively. Participants reported their perceived motion direction using a joystick, allowing us to compare a reference condition to that of the illusion. Results indicate a significant decrease (34%) in theta power (4-7.5 Hz) over the left frontal region during the illusion, complemented by the occurrence of nystagmus in 72% of the trials. These findings align with previous studies linking SD and theta band changes, suggesting implications for EEG-based identification of SD in flight.